Great fight against spam: Make possible to add settings in '.cf' for spamassassin like adding an helping DNSBL and/or modifying scores
The possibility to add DNSBL's is not bad, but not good as without knowing several emails are blocked and in these blocked emails sometimes is a or several hams/emails as false positives. Much better would be being able to put in an '.cf'-configurations-file for spamassassin 'DNSBL's, which do not block but move emails identified as spam to the spam folder. Later on the customer can watch from time to time if hams/femails as alse positives have been sorted out wrongly and put them back to the inbox or a sucfolder which is not for spams.
A rule can even learn from emails which are ham by putting them in a predefined folder like archive or a selfdefined folder where no spams are.
With fine tuning of the simple spamassassin '.cf' I achieved for me and several customers that spam in inbox appears about one time in a week although I have many domains and adresses ad in 2015 I become about 180-220 spams per day (almost all filtered!) ... nowadays it is reduced to about 80-100 spams per day thankfully because of DMARC with their subcomponents.
Yes, I could solve the problem personally in a manual way, but other customers will be very sure happy being able to fight against spam with plesks web interface.
Thank you for your input. SpamAssassin quarantines messages based on certain scoring. Although you can tweak these settings, if you have DNSBL configured your emails get rejected before they reach SpamAssassin. The problem here is with the reject policy of postfix. As far as I am aware those policies are not as flexible as one might want and it is fairly complicated to configure. If you have any suggestion on achieving this particular goal, we would love to hear it. Thank you in advance.
-- SH
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Niels Büttner commented
3 and a half days in second week after some additional adjustments in my 'custom.cf'-file results in 0 spams in inbox and 0 false positives. This happens with all usecases (also my problem child usecase 3). Therefore this is a huge improvement.
And I want to emphasize, this edit is in configuration of spamassassin, which may be connected with amavis daemon and similar, but has nothing to do with configuration of MTA's like postfix.
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Niels Büttner commented
Plesk just has to have the right to write new files or modify created files in /etc/mail/spamassassin/ . All text files with ending '.cf' are obeyed if at least a part of content is good (command 'spamassassin --lint' tells which section is wrong).
Details how to do this manually I wrote in https://talk.plesk.com/threads/possible-to-use-dnsbls-for-moving-identified-email-as-spam-to-spam-folder-not-blocking.375318/post-951518 . I will have to update it as my little updating of 'custom.cf' and adjustment of scorings have made usecase 2 and 3 at least that good like usecase 1 (or better but I did not test long enough).