> Dnia 18.05.2021 o godz. 19:46:30 Juerg Reimann pisze: > > > > I have a customer with a newsletter that has apparently a large number of > > invalid email addresses. When he tries to send mail through my server, > > postfix cuts the smtp session after a while with "too many errors after > > RCPT". > > > > How can I allow him to send his newsletter, even though many false, no > > longer valid email addresses? Preferably I'd like to only allow specified > > hosts and/or authenticated users to be allowed to override the default. > > Does he just send the newsletter as a single message with multiple > recipients? > > Tell him to use some software that will send one message per recipient and > per session. This will take time, but it should be basically one-time job > and will allow him to catch the bounces and remove the bouncing addresses > from his list.
After a bit more investigation I figured that the problem was mostly because of one server of several receivers that threw a TLS handshake error (450). While this should not be much of a problem as postfix should retry to send the mail without encryption, somehow the smtp session was cut with said error. The newsletter is processed by Wordpress, which was configured to send mail directly to my server over port 25, since all are my servers, the ip of this wordpress installation is whitelisted and allowed to relay. So, Wordpress = not too much intelligence in mail processing. I changed the configuration so that Wordpress does not deliver mail directly to port 25 anymore, but logs in as a user over port 587 instead an so gives the mail (in my case) to dovecot-lmtp in between and so - for some reason - things like TLS handshake errors 450 are no problem anymore and are taken care of by postfix... I have yet to test it with the customer, but I think this is probably the quick fix. Of course we have to clean up the addresses in the long run...
