The answer to this as well as other questions concerning operating e-mail services may be found here: FAQ for Internet service providers
The answer to this as well as other questions concerning the sending newsletters and bulk e-mails may be found here: FAQ for e-mail senders
Acceptable Use Policy (AUP): This Acceptable Use Policy (AUP) has been developed to prevent misuse and ensure the usability of the IP services offered. It is binding for all users of Deutsche Telekom's IP services. We ask you to read our AUP carefully and to observe it at all times.
Practical tips on e-mail: Deutsche Telekom has compiled information on how the sending of newsletters or bulk e-mails to customers via t-online.de accounts may be carried out as smoothly as possible. We wish to guarantee reliable delivery yet also effectively prevent spam.
FAQ - Frequently Asked Questions: To help with the troubleshooting and to aid the prompt the clearing of faults, Deutsche Telekom has compiled a list of the most frequently asked questions relevant to our e-mail services for Internet service providers as well as for senders of newsletters and bulk e-mails.
IP troubleshooting: In order that an accurate diagnosis may be accomplished should problems occur, Deutsche Telekom recommends following the series of questions and checks as described here.
Technical information: Deutsche Telekom wishes to promote the exchange of technical information between e-mail providers. Such elements include information about the systems that are currently in production, the dynamic IP-Address ranges reserved for Internet users as well as Information on current spam threats between e-mail providers. You will find the IP addresses of the systems used for t-online.de as well as information concerning our platform protection here.
Contact: Operators of proprietary e-mail services can easily contact us via the provided online forms. Consequently, Deutsche Telekom can ensure the prompt and efficient processing of your requests and queries. When contacting us, please use only the online forms provided for you here. In order to avoid delays and possible confusion, please avoid calling the service hotline intended for users of t-online.de accounts.