I have a mail server running Postfix, Courier, and Roundcube. I'm looking to add the ability for a user to assign their own custom mail filters from the web. I haven't yet found a way I can do this, from what I can tell Roundcube's filter plugin works just like it would on a mail client - that meaning, it has to check the mail before it can filter them.
Any help would be appreciated.
If you can find something that does the Sieve protocol, I think you will have found just what you want. Sieve is a protocol that lets you upload filters to the server and have them applied as the mail is delivered to the users. I have set up Sieve on my server setup (about 2 years ago), but I was using Postfix, Dovecot, and the Sieve plugin for Dovecot. So I'm probably not much direct help, but hopefully it will give you an idea of a direction you could go. I would not be at all surprised if Courier has a Sieve plugin you can set up. Then I guess if you could find a webmail client that lets you set Sieve filters, then you would be all set.
Maybe one of these would be something that would work:
The one thing that concerns me is that I haven't found anything saying how to set up Courier to do Sieve. When I set up my mail server, it was using Dovecot. I did find something on a mailing list about it not supporting Sieve at the time of that message, but couldn't find anything that said either way if current version of Courier can do Sieve.