[enhancement]: Add allow and blocklists for domains and recipients

[alexmbird]

Which feature or improvement would you like to request?

Stalwart's spam filter has constant false-positives for certain domains - for example every single notification gitlab.com sends me ends up in junk. Pasting them into the training UI as ham doesn't solve the problem as this is only a part of the rating system.

Please can there be a way to specify a whitelist of domains [edit: and source IP ranges?] whose emails will never be treated as spam. Ideally this should be exposed in the UI - a simple comma-separated list will do.

The above would be the mimimum to solve the problem I currently experience, but I imagine larger sites might value:

• Wildcards in the allowed domains
• Ability to set a domain whitelist per user/mailbox
• Ability to pair a domain name with a list of IP addresses permitted to send emails for it (otherwise spammers will get wise to spam detection being turned off for badly-configured domains and start to impersonate them)
• Configurable blocklists for domains as well (although a sieve ruleset can handle this case already)

Is your feature request related to a problem?

I'm having a problem with...

All emails from GitLab and several other respectable sources end up in my junk folder.

Code of Conduct

• I agree to follow this project's Code of Conduct

[ghz7l]

Ability to pair a domain name with a list of IP addresses permitted to send emails for it (otherwise spammers will get wise to spam detection being turned off for badly-configured domains and start to impersonate them)

I suppose the SPF record already makes that possible using spf_passed filter or similar.

[mdecimus]

Migrated this to #947