OK, I set up another server, because some of my problems were caused by misconfigured and mixed up local Domains like home.lan and home without .lan (I´m trying a lot at the moment with different computers)... The things are working much better and yes, the test mail ends up in the /var/spool/mail/user file. I used Thunderbird and Outlook to fetch the mail and now they want
to connect, but there is kind of an authentication failure. Here the /var/log/mail.log:
Mar 5 19:17:57 server ipop3d: pop3s SSL service init from 18.104.22.168
Mar 5 19:18:15 server ipop3d: AUTHENTICATE PLAIN failure host=p54B02B59.dip0.t-ipconnect.de [22.214.171.124]
Mar 5 19:18:18 server ipop3d: AUTHENTICATE LOGIN failure host=p54B02B59.dip0.t-ipconnect.de [126.96.36.199]
Mar 5 19:18:26 server ipop3d: Command stream end of file while reading line email@example.com host=p54B02B59.dip0.t-ipconnect.de [188.8.131.52]
Thunderbrid tells me: "Sending of password did not succeed. Mail server domain.tld responded: Bad login".
Uebimiau same as before: "You cannot login with the username and password entered. Please check your username and password and try again."
It is NOT my CAPSLOCK or a similar problem :-). The password I enter is the same that I used in ISPConfig. I tried several times...