@stellated @kkarhan @momo @badkeys It works like this: send an email to a Telekom recipient. Mail bounces with

: host mx03.t-online.de[194.25.134.73] refused to talk to

me: 554 IP=1.2.3.4 - None/bad reputation. Ask your postmaster for help

or to contact tobr@rx.t-online.de for reset. (NOWL)

Send an email to tobr@rx.t-online.de, hilarity ensues.

(They send a reply pointing you to https://postmaster.t-online.de/#t4.1)