manGNUstep - Cookbook: recipe #112, Fighting spam

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recipe #112, Mail Related: Fighting spam

We do consider that fighting spam is an important matter and we take action in that spirit.

During SMTP transaction, DNSBLs and SeeYouLater:

Gna! relies on DNS blacklists to refuse to carry mails from obviously seriously misconfigured or dishonnest SMTPs.

When a mail is found to be sent from a blacklisted host, it is rejected during the SMTP transaction. The host is also added to a temporary local blacklist.

We use several different blacklists:,and (excluding and cases), etc.

The way we use these blacklists block only seriously broken SMTPs or dishonnests SMTP - we do not block personal SMTPs, SMTPs behind endusers IP blocks. If you are victim of a false positive, post a support request and we will do our best to address your issue.

At the following addresses, you can read documentation about the way SMTPs are added to these lists:

We also add to the temporary local blacklists IPs of hosts that sent us mails not strictly addressed to This prove to be a very effective way to fight spam, as our public mail archives shows message-ids (useful for search purpose) that contains non-existent addresses like -unavailable- that spambots grab eagerly.

After mail approval, SpamAssassin filtering:

Every mail transiting at Gna! is filtered by SpamAssassin, unless it was sent by a Gna! server.

Mails considered as spam sent to users aliases are only tagged, with the following specific mail header, which one is pretty usual nowadays:

Mails considered as spam sent to mailing-list are redirected to a special mailing-list, named spam.

Mails redirected to spam are archived on a public area, just in case of falses positives (mail wrongly tagged as spam):

These caught spams are stored in the archives for two months. After that period, they are irremediably trashed.

Mail sent to mailing-list that got a spam score higher than 13 are not archived at all. They are irremediably trashed immediately. This limit has been set to avoid having a spam archiving growing undefinitely each month.

Last update: Tue Oct 31 17:17:14 2006
This recipe comes from Gna! User Docs






Audience and Context

   Anonymous Users, Logged-in Users, All Project Members
   Mailing Lists
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