ISP Mailserver on Blacklist ?!

[Attila]

These blacklists are not reliable and should not get used to block email. Doing so is allowing a private organization to censor your emails.

You can and should use these blacklists as a part of the spamassasin check for spam. If a sender is on such a list, it is a high amount of points in the spamfactor calculation.

There are more and less reliable blacklists. I dunno about surriel. Some others I use, and I do not see false positives.

The worst of all is the DUL list of SORBS, they do block off business users, with legitimate servers in big parts of Asia and Australia. Usually they do not answer any complaints, but justify their actions with flimsy tests and with IEEE drafts, to which a mailserver would not comply. What they do not tell you is that they themselves wrote this IEE draft they're referring to, and to which they want to force you to comply.

If you want to fight spam then use tumgreyspf, a greylisting filter for postfix, or similar. There are no false positives, but 90% or more of thespam does not get through.

Then add spamassasin with clamav, which takes care of the rest.

Some notorious US corporations specialized in spamming, which still get through, you can block by blocking their IP range in postfix access filters.

As a result our customers dare to switch on again catchall email accounts, the amount of spam getting through is no problem anymore.