Can you send mails from webmail?
What are settings (port, etc.) in thunderbird?
Courier->Dovecot is not my special topic, but should be possible without problems. Maybe the the previous error in the installer make some stupid decisions? I dont know.
Just run perl <imscp-1.2.9>/imscp-autoinstall -dr mta and choose dovecot. If an error occurs, think on my words. 
But SMTP is still not working, i can't send mails.
Sorry, my crystal ball is in the garage. Logs, logs and one moment logs. And perhaps a message from your mail-client maybe helpful. 
For the future, have a look in /var/log/imscp/imscp-setup.log when an error occurs.
I can make screenshots of my console. It is better than nothing.
Please post all messages and errors. It is easier for us.
Was sagen denn die entsprechenden Log-Dateien?
Well,
I have tested a little bit. I think max-age is OK. The other questions? Puh, I have no opionion.
BTW: Please check that module headers is enabled a2enmod headers
Was heißt denn "Weg ins Ziel"? Kommen sie an, sind aber als Spam markiert. Oder kommen sie einfach so durch?
Policyd-Weight wäre noch eine Möglichkeit, bzw. in den restrictions von postfix ein paar bekannte und ordentliche Blacklists eintragen.
Grüße
Chris
I think you can use the Donate-Button in Nuxwin signature. Unbelievable. 
Where have I wrote that you have to remove mariaDB? I think you are using it?!? 
And before you can run the installer, apt-get upgrade must run without errors.
Sorry, but if you do not do what your are told, we could not help.
