Allow to maintain local sender blacklist

[rimas-kudelis]

While trying to teach my spamassassin that the newsletters I don't remember subscribing to are in fact spam, I figured out that (being mailing lists) they probably come from same server(s), so instead, why not simply tell Exim to not accept any e-mails coming from these servers. It would be nice to have an example of a black list in our config files.

It seems that in Debian, this is already possible with the local_host_blacklist file, but we could probably copy that mechanism into our non-Debian files as well.

As for v3, the list could probably go into the database instead of being stored in a plain text file.

I think it would be great it we could ban e-mails not just coming from these blacklisted servers, but also having them among the Received headers (to cater for e-mails forwarded from other servers).

Also, it would be great to be able to specify a reason for blacklisting.

This blacklisting should happen after we accept all e-mail for postmaster though.

[Udera]

I normally prefer a maintained blacklist for such issues. Maintaining a manual list for yourself takes a lot of time and is only worth it for very annoying mail servers. We should give the admin the possibilty to black or whitelist a specific server.

[rimas-kudelis]

Yes, I was talking from the admin perspective here. I don't think many normal users would use this feature, even if available.
On the other hand, we could probably make it possible to submit suggestions to the list for the siteadmin to review.