Telekom is a bunch of strange folks. I lately was not able to send mails, from my private mail servrr to my fathers telekom mail. After investigation I found out my server got blocked. After a decade of working. I mailed them, and they told me to register my mailserver with them. I shall tell them what mails I will send from there and about what content. I couldn’t believe my eyes. Sure, thats how mail was supposed to work. Register with every mail server in the world, before you can send mail.

Their mail excerpt: This system has not sent any e-mail to our customers for a long time. For security reasons our systems will only accept e-mails from such IP addresses after a check of setup and information about these systems.

Please give us details about this system and the company using it, tell us all about the sending domain, what type of e-mail will be sent and especially if you or your customer want to send newsletter give us detailed information on how recipients e-mail addresses had been acquired. Who in person is responsible for e-mail sent from this system (MTA)?

Please be advised that only technically proper configured and very well maintained systems are qualified for a reset of reputation and please see our FAQ section 4.1 (Requirements for smooth access to our e-mail exchanges <https://postmaster.t-online.de/index.en.html#t4.1>):

"There must be a domain and website with direct contact information easily deducible from the delivering IP's hostname (FQDN)."