On Fri, 30 Nov 2012, lst_ho...@kwsoft.de wrote:
Zitat von Tomas Macek <ma...@fortech.cz>:
I don't understand now, how Postfix behaves when listenting on submission
port 587.
Our mailserver is sometimes overloaded on port 25, so we want to use
postscreen. But I don't understand, how Postfix works when it's stressed on
port 587, when spammers connect to that opened port and want send their
"emails". In document http://www.postfix.org/STRESS_README.html there is:
NOTE: To avoid "overload" delays for end-user mail clients, enable the
"submission" service entry in master.cf (present since Postfix 2.1), and
tell users to connect to this instead of the public SMTP service.
Should this mean, that Postfix by default does not use counters like
smtpd_hard_error_limit, smtpd_junk_command_limit and maybe others on
sumission port? On this port I would prefer using some kind of smtp auth
and this port should be world accessible to allow the clients using other
networks to authenticate and send emails.
Port 587 is by default nothing special for Postfix because it is mostly a
clone of the Port 25 service. The *intended* difference is that Port 587
should only accept mail by authenticated users, so no chance for spammers if
they don't own valid credentials. To actually see the difference between Port
25 and Port 587 settings you have to compare the entries in master.cf.
Regards
Andreas
OK, so there is a chance for spammers to overload the server using
submission port 587 (the server says then "service "smtp" (25) has
reached its process limit "200"") by exhausting number of available ports
and the MUA clients then can have also problems to send their
emails? I'm I right?
If I'm, then I don't understand, why to split the processes into
submission 587 and normal 25, because if the MUA client send the mail
through 25 (hope with postscreen), there is a chance that the 25 is not
overloaded (because it uses postscreen) and he will be rather
able to send his email compared to 587.
Or I don't still understand something ... :-)
Andreas: sorry for my direct answer to you, my mistake
Tomas
