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Dear list,

I made a patch which extends dovecot-antispam-plugin with support to take the addition and removal of a specific set of flags as trigger for learning.

This allows for very tight integration with Thunderbird and KMail, which both set flags for Junk messages (Thunderbird sets "Junk", KMail sets "JUNK"). With this patch and according configuration, dovecot-antispam-plugin can trigger on the addition (learn as spam) and removal (learn as ham) of these flags.

Combined with a sieve script which sets these flags for incoming mail which has been classified as spam, this allows for a tight and intuitive feedback loop between users and the server-side spam classification system.

I tested that patch with dovecot 2.2 from Debian stretch and so far it works pretty well.

I realise that dovecot-antispam-plugin has not been updated since 2013. It also has not been migrated to Github yet. If it is to be migrated there, I would be happy to submit a pull request there for discussion and merging. Otherwise, someone would have to indicate how to go forward with applying this patch to the official version, if that is desired.

The patch is based on current tip and feedback is appreciated. I took some inspiration from dovecot-core/src/plugins/notify/notify-storage.c -- this requires the use of struct mail_private to be able to override the vfunc for mail_update_keywords, which I actually do not like. However, when I tried to make this patch base on the use of the notify plugin (via notify_register), I ran into the issue that the transaction is partially freed before the transaction_commit event from notify is emitted, which is unfortunate and breaks at least the mailtrain backend (which I use). This is in theory fixable, but I wanted to keep the patch as small as possible, as I have no idea whether this will eventually end up upstream or whether I’ll have to maintain that for myself.

If upstream is not interested in this patch, please let me know! In that case, I would consider making an own plugin, which fewer backends (possibly only a mailtrain-like one) out of this, but frankly, I would consider that a waste of resources.

In the hope that this is useful for others and hoping for feedback, Jonas Wielicki -----BEGIN PGP SIGNATURE-----

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