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postmaster.t-online.de

1.Acceptable Use Policy (AUP)
2.FAQ for users at t-online.de
3.Practical tips for senders of e-mails
4.Notes for mail server operators
5.Information on sending mass e-mails (e-mail marketing)
6.IP troubleshooting - troubleshooting at IP level
7.Technical information
8.Contact

Use the "↑" above the headings on the right-hand edge to return to the relevant heading within the content
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1.Acceptable Use Policy (AUP)
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2.FAQ for users at t-online.de
2.1 FAQ for users at t-online.de
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3.Practical tips for senders of e-mails
3.1 Pay attention to technical standards
3.2 Create transparency when sending newsletters
3.3 Avoid your e-mails being regarded as spam, harmful code and phishing
3.4 Despite using the right address, the e-mail I have sent does not arrive. What can I do?
3.5 Do t-online.de systems use greylisting, SPF or DKIM for e-mail filtering?
3.6 How can I find out personal data for an e-mail address at t-online.de?
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4.Notes for mail server operators
4.1 Requirements for smooth access to our e-mail exchanges
4.2 Manage the blacklists and whitelists proactively
4.3 Secure your e-mail servers against misuse
4.4 In the event of a fault, first check the logs of your SMTP server
4.5 Why do e-mails from our customers only arrive at t-online.de addresses with a delay?
4.6 Why are e-mails from our server not accepted by the t-online.de servers?
4.7 Why was the establishment of an SMTP connection rejected by the t-online.de server?
4.8 My IP address is blocked due to spam that was forwarded by my server, but does not originate from me. Can I do anything to prevent this?
4.9 Can I use the t-online.de systems’ mail filters too?
4.10 Does Telekom provide a feedback loop?
4.11 How can I be placed on the whitelist?
4.12 Reputation management
4.13 How can I reach the Postmaster for t-online.de systems?
4.14 I have reported an error and have not yet received confirmation. What happened?
4.15 What IP ranges do the t-online.de dial-ups and outbound mail servers use?
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5.Information on sending mass e-mails (e-mail marketing)
5.1 What general information should I be aware of if I want to send mass e-mails?
5.2 Requirements for smooth access to our e-mail exchanges
5.3 Measures if rules are disregarded
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6.IP troubleshooting - troubleshooting at IP level
6.1 General
6.2 Checking the IP addresses
6.3 Checking the IP connection
6.4 Checking the SMTP dialog
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7.Technical information
7.1 Mail servers (t-online.de)
7.2 Dynamic IP ranges
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8.Contact
 
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1.Acceptable Use Policy (AUP)

An Acceptable Use Policy (AUP) is a set of rules published by the owner of a network and operator of services that specifies the manner in which the network and services may be used. Telekom’s AUP was published at postmaster.t-online.de/aup.en.html.
 
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2.FAQ for users at t-online.de
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2.1FAQ for users at t-online.de
You can find comprehensive information on using our e-mail services at: http://www.telekom.de/hilfe/festnetz-internet-tv/e-mail.
 
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3.Practical tips for senders of e-mails
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3.1Pay attention to technical standards
Telekom expects compliance with technical standards when transmitting e-mails, as published by the Internet Engineering Task Force (IETF) of the Internet Society (ISOC), including the RFCs for SMTP, the "Internet Message Format" and Forward-confirmed reverse DNS. Make sure that your e-mail systems meet these standards.
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3.2Create transparency when sending newsletters
Strict legal requirements apply to mass e-mails sent for commercial purposes (Guidelines). To avoid newsletters being categorized as spam, they need to meet at least the following formal requirements:
  • The addressee must be able to tell which of his e-mail addresses was contacted.
  • To meet the transparency requirement for commercial mailings, the newsletter must contain a declaration that indicates where the address you wrote to came from and why you believe you are entitled to send newsletters to this address.
  • Only write to recipients who have personally given you permission to do so. ("Personally" means that a declaration of consent submitted to a third party cannot be transferred. Keyword: "Address trading".) Important: In the case of e-mail addresses generated via opt-in, check that they actually belong to the person who provided them. In practice, this almost always results in a double opt-in procedure.
  • Every newsletter must contain an opt-out declaration. This means you must inform the recipients about how to unsubscribe from the newsletter if they no longer wish to receive it.
  • In the case of mass commercial e-mails, publication details must be provided. (The free "Impressum Generator" provided by Juraforum, for example, could be useful for this.)
  • Ensure that your e-mail distribution lists are always up to date. Avoid bounce e-mails (non-delivery notifications), establish suitable bounce handling and delete an e-mail address immediately if you know that the relevant user does not or no longer exists.
Notes:
  • The first item already means that addressing e-mails using blind carbon copies (BCC) is not permitted.
  • The transparency declaration and opt-out declaration are usually summarized at the end of the e-mail before the imprint.
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3.3Avoid your e-mails being regarded as spam, harmful code and phishing
  • Avoid using obfuscation and spam techniques as criminals do (hash buster, masking, changing, missing or incorrect sender details etc.) and do not use bulk mailer software using such techniques.
  • Use meaningful URLs and avoid unnecessary coding.
  • Only link to valid, trustworthy URLs within your e-mail and avoid the use of redirects and URL shortening services (shortcomings).

    URLs from services that are known to be abused (see: http://www.surbl.org/tld) are rejected by our spam filter to protect our customers.
  • Never link to a phishing website and do not forward links to harmful software or cite spam, not even as an example or for fun!
  • For security reasons our servers don't allow unencrypted transfer of executable scripts and attachments.

    This includes: ade, adp, app, asp, bas, bat, bhx, cab, ceo, chm, cmd, com, cpl, crt, csr, der, exe, fxp, hlp, hta, iframe, inf, ins, isp, its, js, jse, lnk, mad, maf, mag, mam, mar, mas, mat, mde, mim, msc, msi, msp, mst, ole, pcd, pif, reg, scr, sct, shb, shs, vb, vbe, vbmacros, vbs, vsw, wmd, ws, wsc, wsf, wsh and xxe.

    Rename file extensions, if you still need to send executable files or scripts. (As an alternative a cloud service such as Dropbox, OneDrive or our own MagentaCLOUD is more appropriate. The latter is included with all our mailboxes for free and easily allows transfers to and from others.)
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3.4Despite using the right address, the e-mail I have sent does not arrive. What can I do?
If our e-mail system cannot deliver an e-mail even after the delivering system has accepted it, you will automatically be informed via a bounce message (non-delivery notification). If you have not received an error message, the t-online.de systems were able to deliver your e-mail to the recipient’s inbox.
  • Perhaps your e-mail was classified as spam and is in the recipient's spam folder.
  • Ensure you use your valid e-mail address as the envelope sender ("mail from") to avoid receiving any bounce e-mails.
  • Ensure that the e-mail coding complies with the standards.
  • t-online.de accounts can receive e-mails up to a maximum size of 50 megabytes. The size relates to the entire e-mail, i.e. the header, the actual text of the e-mail as well as the formatting and any attachments.
  • If the recipient has set up e-mail forwarding, your e-mail will be forwarded there. You may receive a bounce e-mail from another provider after a few minutes. Please check this message and note that Telekom cannot resolve any errors that this other provider may have.
  • If your e-mail meets all the requirements and yet still does not arrive, you can find further tips under "Checking the SMTP dialog".
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3.5Do t-online.de systems use greylisting, SPF or DKIM for e-mail filtering?
Greylisting is generally understood to mean that every incoming e-mail is initially rejected temporarily and only accepted after a renewed delivery attempt. This is based on the assumption that only authorized e-mail systems initiate renewed delivery of rejected e-mails. As greylisting cannot actually identify unauthorized e-mails and also hinders the delivery of legitimate e-mails, Telekom systems do only use this procedure against repeatedly suspicious systems and potential abuse.

The Sender Policy Framework, SPF for short, can enable a check to determine whether the sending IP address is authorized to send e-mails for the domain in question. This procedure has numerous vulnerabilities that cannot be compensated for, including those that are described here. Therefore, Telekom does not use SPF either passively (when receiving e-mails) or actively (for sending) by creating corresponding DNS resources.

Until now, we have neither used nor evaluated DKIM signatures. (An exception is the "Trusted Dialog" project, which uses DKIM signatures for "inbox branding".)
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3.6How can I find out personal data for an e-mail address at t-online.de?
Telekom does not disclose any personal data for its customers’ e-mail addresses. Such information is always treated as strictly confidential. You can find Telekom's official data protection guidelines here.
 
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4.Notes for mail server operators

We require mail server operators to take account of the recommendations provided in the "Practical tips for senders of e-mails" section, if appropriate.
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4.1Requirements for smooth access to our e-mail exchanges
There must be a domain and website with direct contact information easily deducible from the delivering IP's hostname (FQDN). (see RFC 1912, FCrDNS, EU Directive 2000/31/EC Article 5)

We recommend that users of dialups, cloud and other anonymous systems use a mail gateway (SMTP relay) from a suitable provider.

We expect you to treat the resources provided with as much respect as possible. Please keep the number of simultaneously opened TCP/IP connections on a server or a server cluster (IP subnet) to a minimum.

In the case of unusual traffic volume, concealment and deception, we reserve the right to restrict and, if necessary, suspend the receipt of e-mails.
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4.2Manage the blacklists and whitelists proactively
The automated use of an external blacklist always carries the risk of also preventing legitimate communication. Even though the term "blacklist" suggests a black and white judgment, it is advisable to use several criteria. You should at least remove known e-mail services from automated filtering by using your own whitelist.
  • Use extreme caution when selecting any external blacklist that you plan to use.
  • To counteract any unwanted blacklisting, either maintain your own whitelist or integrate an external list, such as the DNSWL. (Of course, our servers that send e-mails are also listed there.)
Only through proactive management of the blacklists and whitelists you use can you ensure that your users actually receive the desired e-mails. You can find information on selecting and using suitable blacklists in the Internet standards "Overview of Best Email DNS-Based List (DNSBL) Operational Practices" and "DNS Blacklists and Whitelists" from the Anti-Spam Research Group (ASRG).
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4.3Secure your e-mail servers against misuse
  • Ensure that your servers are not set up as open proxy or open relay and that they do not forward any e-mails that you receive from open relay or open proxy connections.
  • Always keep your software up to date to prevent misuse of your resources and protect yourself against damage to your good reputation.
  • Use filters for outgoing e-mail as well to reduce the dispatch of junk mail (spam and e-mails containing viruses).
  • Do not use Sender Address Verification to check that the sender addresses of incoming e-mails exist. The procedure used is not standardized and it is not possible to distinguish this procedure from, for example, that of a spammer who "washes" his address list.
  • It is vital to avoid what is known as "backscatter" by rejecting incoming e-mails to non-existent recipients in the SMTP dialog; furthermore, your content filter against junk mail must also not generate any bounce e-mails (non-delivery notifications). This means that filtering must be performed before an e-mail is received so that it can be rejected if necessary. (For information on how to configure this, please see the documentation for your mail server. You can find guides for Exchange, for example, at hhttp://www.experts-exchange.com/articles/4257/Exchange-2007-2010-Backscatter-and-how-to-resolve-it.html and for Postfix at http://www.postfix.org/SMTPD_PROXY_README.html.)
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4.4In the event of a fault, first check the logs of your SMTP server
The SMTP protocol defines response codes that provide information on the status and the recommended next steps. If error messages occur regularly or even permanently, these indicate errors that should be analyzed in more detail urgently. Checking your SMTP logs is always the basis for further measures. We try to output sufficiently descriptive error messages.

If you need our support in eliminating errors, we ask that you attach suitable extracts from the log files to your communication. Without the original error message, we cannot investigate the error.
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4.5Why do e-mails from our customers only arrive at t-online.de addresses with a delay?
If e-mail delivery to your server is frequently delayed with a temporary error ("421 Maximum parallel connections for your IP-Address reached"), this means that the delivering server has established too many connections to our server at the same time. Therefore, when your system receives the error message, there are already multiple connections that are being used to transfer e-mails. Please configure your mail server(s) so that a new connection is not established for every e-mail, and the number of messages to be transferred via one connection is not restricted unnecessarily. (Keywords: "peer concurrency" and "destination concurrency")
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4.6Why are e-mails from our server not accepted by the t-online.de servers?
If you have received a 5xx-SMTP error message:
  • Check your e-mail queues to see if there is any unusual sending behavior or even a permanent fault. In these cases, acceptance of e-mails from the IP addresses concerned is temporarily restricted or even permanently suspended.
  • The t-online.de servers do not allow dynamic IP addresses and IP addresses that do not comply with the common Internet standards from establishing an SMTP connection. Therefore, ensure that your e-mail systems comply with these standards.
  • If you frequently receive the error message "550-5.7.0 Message considered as spam or virus, rejected [...]", it is vital that you prevent your server from continuing to deliver these e-mails that have been categorized as spam. The error message specifies a dedicated contact partner for any e-mails that are incorrectly categorized as spam. Resume delivery only once the problem has been resolved!
If you have received a 4xx-SMTP error message:
  • An unusually high load on the Telekom servers can temporarily result in the error message "System temporarily unavailable". Please accept our apologies for this. Such a fault is rare and is corrected promptly by our technicians.
  • If the IP session limit is exceeded, please minimize the number of TCP/IP connections opened at the same time on your server or server cluster (IP subnet).
In the event of interruption to communication at IP level:

To determine the cause of a serious fault, the following questions must be answered:
  • Are your systems receiving the correct IP addresses from the DNS resolver?
  • Can your systems access the t-online.de mail servers at IP level?
  • If your server is attempting to deliver encrypted e-mails, please check whether the TLS handshake is successful (correct certificate, DANE).
To be able to provide reliable information on the fault in question, it is recommended that you carry out the tests necessary to answer these questions and note the correct order. We have described the procedure in detail under "IP troubleshooting - troubleshooting at IP level".
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4.7Why was the establishment of an SMTP connection rejected by the t-online.de server?
If the t-online.de server terminates an SMTP connection after outputting the message "554 IP=[SENDER-IP] - A problem occurred. [...]", the specified IP address is blocked from delivering e-mails. A block may be in place, in particular, if you want to use an IP address that you have not previously used for sending e-mails; this may therefore have been caused a long time ago.

With some MTAs, the relevant error message may not appear on your system because the t-online.de server disables the connection immediately after outputting the message and older systems class this behavior as a temporary error, meaning that further delivery attempts will be made according to the configuration of these MTAs.

If you have resolved the problem that caused the error or do not believe there is a problem, please contact the dedicated contact person specified in the error message. You can also reach this person via any of our listed systems. Alternatively, you can use our online form to contact us.
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4.8My IP address is blocked due to spam that was forwarded by my server, but does not originate from me. Can I do anything to prevent this?
We expect all ISPs that deliver e-mails to our servers to use suitable anti-spam technologies to minimize spam. Please resolve the existing problem and then contact the dedicated contact person specified in the error message. You can also reach this person via any of our listed systems.
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4.9Can I use the t-online.de systems’ mail filters too?
Telekom does not offer external access to its in-house mail filters and mail filter technologies. Among others, t-online.de systems use the mail classification eXpurgate from "Cyren".
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4.10Does Telekom provide a feedback loop?
We cannot provide a feedback loop due to data protection provisions.
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4.11How can I be placed on the whitelist?
Telekom does not offer any whitelisting. If you are blocked and believe that there is no (longer) cause for this, please contact the dedicated contact person specified in the error message. You can also reach this person via any system that is otherwise blocked for e-mail delivery.

In cases in which there are frequent, temporary blocks, the cause is often one of the following: If none of the above applies, but your server is still frequently rejected temporarily, please send an e-mail to our postmaster (see the next item for more information), specifying the IP addresses of your systems that deliver e-mails.
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4.12Reputation management
To optimize the reputation of your mail systems, remove their IP addresses from relevant public DNSBLs, such as SpamCop, Spamhaus, NixSpam, etc. (Blacklist check services such as MXToolbox and MultiRBL may be useful for checking this.)

You can also inquire about the reputation of your mail server using services such as Sender Score, Talos Reputation Center, Mailspike and BarracudaCentral and enter the IP addresses of your mail servers in public whitelists, such as DNSWL.
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4.13How can I reach the Postmaster for t-online.de systems?
You can reach our postmaster at postmaster@t-online.de (If your system is suspended from sending mail to t-online.de addresses, please use postmaster@rx.t-online.de instead).
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4.14I have reported an error and have not yet received confirmation. What happened?
Errors reported to Telekom are dealt with promptly. If high loads should occasionally lead to delays, please accept our apologies. Furthermore, we do not send confirmation of receipt; if necessary, we will get back to you. Please understand that we cannot provide any information on the processing status for a specific customer, due to data privacy reasons.
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4.15What IP ranges do the t-online.de dial-ups and outbound mail servers use?
You can find the IP ranges of the dial-ups and the IP addresses of the t-online.de mail servers here.
 
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5.Information on sending mass e-mails (e-mail marketing)

We expect senders of bulk e-mails to take account of the recommendations provided in the "Practical tips for e-mail senders" and "Notes for mail server operators" section, if appropriate.
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5.1What general information should I be aware of if I want to send mass e-mails?
For more information to help you optimize your e-mail communication and avoid confusion with unwanted spam, see the links below:
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5.2Requirements for smooth access to our e-mail exchanges
E-mails and newsletters sent automatically must also offer all addressees the option of directly opting out in the e-mail concerned.

To deliver mass commercial e-mails, in particular, you require the explicit and personal(!) agreement of the recipient. For practical reasons, this agreement to receive a particular e-mail is obtained almost exclusively by means of double opt-in procedures. (In 2008, the German Federal Court of Justice judged opt-out only procedures to be illegal in Germany.)

Therefore, please delete or block all e-mail addresses...
  • for which you cannot provide evidence that will stand up in court of a correctly performed double opt-in procedure (or a similar alternative procedure) and all e-mail addresses that you have not been in contact with for longer than three months. (Since the update to the German Data Protection Act (BDSG) in 2009, the personal consent of the person concerned must be sought, e.g. by means of a double opt-in procedure. This also applies to old data since August 31, 2012, when the transition deadline was reached. In addition, false or incorrect data must be deleted or blocked.)
  • for which you receive rejections during delivery and bounce mails (non-delivery notifications). If our e-mail systems inform you in the SMTP dialog that the user is unknown ("hard bounce"), you must delete or block the e-mail address in question from your lists.
If you send mass e-mails on behalf of others, please use dedicated IP addresses, in particular for customers whose respectability is in doubt, to reduce the impact of a potential block.
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5.3Measures if rules are disregarded
We reserve the right to temporarily restrict the acceptance of e-mails from the IP addresses concerned in the event of unusual traffic volumes, or to suspend acceptance in the event of permanent faults. You will then receive error number 554 in the SMTP dialog; a contact person is also specified in the error message. (For details, see section "Checking the SMTP dialog"):
  • For a professional sender of e-mails, we expect the share of SMTP error messages to be 3 % at most, and no more than 1.5 % on average. Higher bounce rates are an indication of outdated e-mail addresses or lack of verification via double opt-in, which we consider to be misuse.
  • If our spam protection classes certain e-mails as "spam", these are rejected during transmission following the DATA phase with the error message "550-5.7 0 Message considered as spam or virus, rejected [...]". You must then immediately prevent your server from continuing to deliver these e-mails that have been classed as spam. The error message specifies a dedicated contact partner for any e-mails that are incorrectly evaluated as spam. Continue delivery only once the problem has been resolved!
  • Addressing for our spam traps.
  • Likewise, any customer complaints that we receive may result in the same measures.
A block may be in place, in particular, if you want to use an IP address that you have not previously used for sending e-mails; this may therefore have been caused a long time ago. At IP level, connections are not rejected, but an error message will always be output. To resolve any technical issues, see section IP troubleshooting - troubleshooting at IP level.
 
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6.IP troubleshooting - troubleshooting at IP level
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6.1General
To determine the cause of a serious fault, the following questions must be answered:
  • Are your systems receiving the correct IP addresses from the DNS resolver?
  • Can your systems access the t-online.de mail servers at IP level?
  • If your server is attempting to deliver encrypted e-mails, please check whether the TLS handshake is successful (correct certificate, DANE).
  • Do t-online.de servers accept e-mails from your systems?
These checks should be carried out in the order specified. If you find an error you must eliminate it first before you can perform the other checks in a meaningful manner.
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6.2Checking the IP addresses
If you are using Windows, UNIX or Linux, you should receive the t-online.de IP addresses of the mail servers (MX) when you enter the command 'nslookup -type=mx t-online.de' on your computer.

C:\WINDOWS>nslookup -type=mx t-online.de
Server: ...
Address: ...
Non-authoritative answer:
t-online.de MX preference = 10, mail exchanger = mx00.t-online.de
t-online.de MX preference = 10, mail exchanger = mx01.t-online.de
t-online.de MX preference = 10, mail exchanger = mx02.t-online.de
t-online.de MX preference = 10, mail exchanger = mx03.t-online.de

mx00.t-online.de internet address = 194.25.134.8
mx01.t-online.de internet address = 194.25.134.72
mx02.t-online.de internet address = 194.25.134.9
mx03.t-online.de internet address = 194.25.134.73

C:\WINDOWS>

Your results should match those shown above, although the order may be different. If you receive different results, you must check your DNS infrastructure, since your systems and/or the systems of your Internet service provider could be compromised.
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6.3Checking the IP connection
E-mails are usually delivered via several hops (stations/network nodes on the Internet) and may therefore pass from the area of responsibility of your own ISP (Internet service provider) to that of another ISP. A fault at IP level can occur with any hop, meaning that an error when delivering e-mails from your systems to the t-online.de domain may also fall under another ISP's area of responsibility.

If you are using Windows, you can use the command 'tracert mx00.t-online.de' to trace the specific route of the IP data packets and thus check the connection between your client and the e-mail servers of the t-online.de domain. For UNIX or Linux, the command 'traceroute mx00.t-online.de' is available for this check.

In our first example, there is no fault and the IP data packets reach the target computer:

C:\WINDOWS>tracert mx00.t-online.de

Tracing route to mx00.t-online.de [194.25.134.8] over a maximum of 30 hops:

1 <1 ms 1 ms <1 ms ..............
2 51 ms 46 ms 40 ms .............
3 41 ms 40 ms 41 ms 217.0.76.42
4 47 ms 45 ms 46 ms 0113699-1-1-gw.ULM.DE.net.DTAG.DE [194.25.10.94]
5 46 ms 48 ms 46 ms 217.6.25.154
6 46 ms 48 ms 46 ms mx00.t-online.de [194.25.134.8]
Trace complete.

C:\WINDOWS>

If the target IP address cannot be reached, there is an error at IP level and you receive a result with failure due to timeout, similar to the following example:

C:\WINDOWS>tracert mx00.t-online.de

Tracing route to mx00.t-online.de [194.25.134.8] over a maximum of 30 hops:

1 <1 ms 1 ms <1 ms ..............
2 51 ms 46 ms 40 ms .............
3 46 ms 48 ms 46 ms 62.156.138.89
4 * * * Request timed out.
5 * * * Request timed out.
.
.
29 * * * Request timed out.
30 * * * Request timed out.

Trace complete.

C:\WINDOWS>

You can identify the last network node actually reached in the result of the 'tracert mx00.t-online.de' command. Please note that this network node may under certain circumstances be in the area of responsibility of an external Internet service provider and that only the operator of the relevant network node is the correct contact for eliminating such an error at IP level. If you have problems clarifying responsibility, please consult your network specialist, your Internet service provider or your peering partner.

In the example shown above, the hop last reached is the IP address 62.156.138.89, a system in the Deutsche Telekom AG (DTAG) network. Only in cases such as these, in which the last network node that can be reached is actually Telekom's responsibility, can the Postmaster team responsible for t-online.de support you.
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6.4Checking the SMTP dialog
If you can reach the t-online.de mail server (MX) using the command 'tracert mx00.t-online.de', there is no technical fault at IP level. In this case, it can only be an error that occurs at Simple Mail Transfer Protocol (SMTP) level during an attempt to transmit data. Such an error should be found in the log of your e-mail system. Information on the Simple Mail Transfer Protocol can be found online at http://www.rfc-editor.org/rfc/rfc5321.txt.

You can also check the communication between your client and the t-online.de mail server manually. To do this, a connection to the t-online.de mail server must first be established using the command 'telnet 194.25.134.8 25. Via this Telnet connection, you can then manually transfer a message in accordance with SMTP and trace each individual step. For a reliable check you should use your original HELO and transfer the exact e-mail that failed to be delivered previously.

Note: With some versions of Windows, the telnet command first has to be installed. For detailed information on this, see Microsoft TechNet: Windows 7: Enabling Telnet Client

Example of error-free e-mail transmission:

C:\WINDOWS>telnet 194.25.134.8 25
Trying 194.25.134.8...
Connected to 194.25.134.8.
Escape character is '^]'.
220-mailin06.aul.t-online.de T-Online ESMTP receiver fssmtpd2025 ready.
220 T-Online ESMTP receiver ready.
HELO myname.mydomain.example
250 Ok.
MAIL FROM: <sender@demo.example>
250 2.1.0 Sender accepted.
RCPT TO: <a@t-online.de>
250 2.1.5 Recipient accepted.
DATA
354 Ok, start with data.
Subject: A test

And the body here

Best regards
.
250 2.0.0 Message accepted.
QUIT
221-2.0.0 mailin06.aul.t-online.de closing.
221 2.0.0 Closing.
Connection closed by foreign host.
C:\WINDOWS>

Errors which occur during the SMTP dialog are displayed with an appropriate message. In the event of exceptional e-mail volumes on the client-side, you will see one of the two error messages shown below.

Error message 554 (IP blocking):

C:\WINDOWS>telnet 194.25.134.8 25
Trying 194.25.134.8...
Connected to 194.25.134.8.
Escape character is '^]'.
554 IP:87.167.75.190 - A problem occurred. (Ask your postmaster for help or to contact tosa@rx.t-online.de to clarify.)
Connection closed by foreign host.
C:\WINDOWS>

If you receive the above error message with ID 554, the t-online.de systems are currently not accepting any e-mails with the IP address that your clients use. This IP blocking can be traced back to a previously observed unusual volume of e-mails at the IP address concerned.

If you suspect that e-mails from one of your IP addresses are being rejected by the t-online.de systems by mistake, we ask that you use our online form and notify us of the IP concerned. We can then check what the cause of the IP blocking was and, where necessary, modify our system settings.

Error message 550 (suspected spam):

C:\WINDOWS>telnet 194.25.134.8 25
Trying 194.25.134.8...
Connected to 194.25.134.8.
Escape character is '^]'.
220-mailin16.aul.t-online.de T-Online ESMTP receiver fssmtpd2025 ready.
220 T-Online ESMTP receiver ready.
HELO myname.mydomain.example
250 Ok.
MAIL FROM: <someone@demo.example>
250 2.1.0 Sender accepted.
RCPT TO: <a@t-online.de>
250 2.1.5 Recipient accepted.
DATA
354 Ok, start with data.
Date: Mon, 6 Oct 2003 12:08:47 +0200
Subject: get it for FREE !

... some SPAM here ...
.
550-5.7.0 Message considered as spam or virus, rejected
550-5.7.0 Your IP: 87.167.75.190
550-5.7.0 Mailhost: mailin52.aul.t-online.de
550-5.7.0 Timestamp: 2014-03-30T11:54:48Z
550-5.7.0 Expurgate-ID: 149288::1582806291-000010EB-AB4F98D6/0/15928480883
550-5.7.0 Authenticator: 823C90685334AF27D88C5A4057FBAB4ED18EA9C983A0E2427F875…
550-5.7.0
550-5.7.0 Your message has been rejected due to spam or virus classification.
550-5.7.0 If you feel this is inapplicable, please report the above error codes
550-5.7.0 back to FPR@RX.T-ONLINE.DE to help us fix possible misclassification.
550-5.7.0 We apologize for any inconvenience and thank you for your assistance!
550-5.7.0
550-5.7.0 Die Annahme Ihrer Nachricht wurde abgelehnt, da sie als Spam oder
550-5.7.0 Virus eingestuft wurde. Sollten Sie dies als unzutreffend ansehen,
550-5.7.0 senden Sie bitte obige Fehlercodes an FPR@RX.T-ONLINE.DE, damit wir
550-5.7.0 die Klassifizierung untersuchen koennen. Wir entschuldigen uns fuer
550 5.7.0 etwaige Unannehmlichkeiten und bedanken uns fuer Ihre Unterstuetzung!
QUIT
221-2.0.0 mailin16.aul.t-online.de closing.
221 2.0.0 Closing.
Connection closed by foreign host.
C:\WINDOWS>

If a specific e-mail is classified as spam, acceptance is rejected in compliance with the RFCs.

If your e-mail has been classified as spam and you consider this to be an error, please use our online form and forward the e-mail to us with all the header lines. We can then check what the cause of the assessment was and whether an incorrect assessment has been made.

Special case: timeout:

C:\WINDOWS>telnet 194.25.134.8 25
Trying 194.25.134.8...
Connected to 194.25.134.8.
Escape character is '^]'.
220-mailin18.aul.t-online.de T-Online ESMTP receiver fssmtpd2025 ready.
220 T-Online ESMTP receiver ready.
HELOConnection closed by foreign host.
C:\WINDOWS>

If the delivering client does not respond within six seconds of connecting, it is immediately disconnected. For manual transmission, you should therefore write quickly or use cut & paste.

This kind of error may also be caused by your client, for example if an outdated software version is used.
 
↑
7.Technical information
↑
7.1Mail servers (t-online.de)
In the interests of our numerous trustworthy customers, we ask you to whitelist our mailouts named here and in order to cooperate closely in the case of established misuse, to clarify any possible disruption to e-mail delivery as quickly as possible. In the event of misuse, please send your message to: <abuse@telekom.de>.

You can find the IP addresses of the dynamic IP ranges used for our customers under dynamic IP ranges.

Name:IP address:
mailout00.t-online.de   194.25.134.16
mailout02.t-online.de194.25.134.17
mailout04.t-online.de194.25.134.18
mailout06.t-online.de194.25.134.19
mailout08.t-online.de194.25.134.20
mailout10.t-online.de194.25.134.21
mailout12.t-online.de194.25.134.22
mailout01.t-online.de194.25.134.80
mailout03.t-online.de194.25.134.81
mailout05.t-online.de194.25.134.82
mailout07.t-online.de194.25.134.83
mailout09.t-online.de194.25.134.84
mailout11.t-online.de194.25.134.85
mailout13.t-online.de194.25.134.86
↑
7.2Dynamic IP ranges
We assign the following IP ranges dynamically to our customers for their Internet access (dialup). E-mails from these IPs should be accepted only following previous authentication (Message Submission, see RFC 4409). This allows these IP ranges to be easily blocked on MX servers by means of a blacklist. You can find these in the Spamhaus PBL, for example, so you do not have to maintain the entries separately. The IP addresses that our servers use for correct outgoing e-mails can be found under Mail server.

62.224.0.0 - 62.224.127.255DTAG-DIAL1Deutsche Telekom AG
62.224.128.0 - 62.224.255.255DTAG-DIAL1Deutsche Telekom AG
193.158.128.0 - 193.158.191.255DTAG-DIAL2Deutsche Telekom AG
193.159.0.0 - 193.159.158.255DTAG-DIAL3Deutsche Telekom AG
194.25.237.0 - 194.25.237.255DTAG-DIAL5Deutsche Telekom AG
62.156.0.0 - 62.156.63.255DTAG-DIAL6Deutsche Telekom AG
212.184.128.0 - 212.184.165.255DTAG-DIAL7Deutsche Telekom AG
62.158.0.0 - 62.158.255.254DTAG-DIAL8Deutsche Telekom AG
212.185.208.0 - 212.185.255.255DTAG-DIAL9Deutsche Telekom AG
62.155.128.0 - 62.155.247.255DTAG-DIAL10Deutsche Telekom AG
62.155.254.0 - 62.155.255.255DTAG-DIAL10Deutsche Telekom AG
62.153.0.0 - 62.153.43.255DTAG-DIAL11Deutsche Telekom AG
62.225.192.0 - 62.227.255.254DTAG-DIAL12Deutsche Telekom AG
217.0.0.0 - 217.5.127.255DTAG-DIAL13Deutsche Telekom AG
217.80.0.0 - 217.86.127.255DTAG-DIAL14Deutsche Telekom AG
217.87.0.0 - 217.89.23.255DTAG-DIAL14Deutsche Telekom AG
217.224.0.0 - 217.237.161.47DTAG-DIAL15Deutsche Telekom AG
80.128.0.0 - 80.146.159.255DTAG-DIAL16Deutsche Telekom AG
217.238.0.0 - 217.239.36.255DTAG-DIAL17Deutsche Telekom AG
217.246.0.0 - 217.255.255.255DTAG-DIAL17Deutsche Telekom AG
217.94.96.0 - 217.95.255.255DTAG-DIAL18Deutsche Telekom AG
217.244.64.0 - 217.245.255.255DTAG-DIAL18Deutsche Telekom AG
84.128.0.0 - 84.135.255.255DTAG-DIAL19Deutsche Telekom AG
217.93.0.0 - 217.94.63.255DTAG-DIAL19Deutsche Telekom AG
84.136.0.0 - 84.191.255.255DTAG-DIAL20Deutsche Telekom AG
87.160.0.0 - 87.186.159.255DTAG-DIAL21Deutsche Telekom AG
87.186.192.0 - 87.189.255.255DTAG-DIAL22Deutsche Telekom AG
91.0.0.0 - 91.23.255.255DTAG-DIAL22Deutsche Telekom AG
87.190.128.0 - 87.190.191.255DTAG-DIAL23Deutsche Telekom AG
91.32.0.0 - 91.63.255.255DTAG-DIAL23Deutsche Telekom AG
79.192.0.0 - 79.244.191.255DTAG-DIAL24Deutsche Telekom AG
79.245.0.0 - 79.247.255.255DTAG-DIAL25Deutsche Telekom AG
93.192.0.0 - 93.223.255.255DTAG-DIAL25Deutsche Telekom AG
87.140.224.0 - 87.141.213.255DTAG-DIAL26Deutsche Telekom AG
87.141.224.0 - 87.159.255.255DTAG-DIAL26Deutsche Telekom AG
79.252.0.0 - 79.255.255.255DTAG-DIAL27Deutsche Telekom AG
79.248.0.0 - 79.251.255.255DTAG-DIAL28Deutsche Telekom AG
93.224.0.0 - 93.239.255.255DTAG-DIAL28Deutsche Telekom AG
87.137.192.0 - 87.137.255.255DTAG-DIAL29Deutsche Telekom AG
87.130.128.0 - 87.135.255.255DTAG-DIAL100Deutsche Telekom AG
217.240.0.0 - 217.242.191.255DTAG-DIAL101Deutsche Telekom AG
93.242.0.0 - 93.247.127.255DTAG-DIAL102Deutsche Telekom AG
93.247.128.0 - 93.247.255.255DTAG-DIAL103Deutsche Telekom AG
93.252.0.0 - 93.255.255.255DTAG-DIAL103Deutsche Telekom AG
217.90.0.0 - 217.90.255.255DTAG-DIAL103Deutsche Telekom AG
 
↑
8.Contact

Please use our contact form.




© Deutsche Telekom AG