Postfix Spam and Postfix Access
You receive a spam email, or how they say - email newsletter you have subscribed for... You click unsubscribe, and next morning you find even more spam emails in your mailbox. What has happened is that now you have told spammers that your e-mail address is alive and spam emails reach to you. Your valuable email address is resold further to hordes of other email spammers.
One way is to let Postfix deal with the spam. Postfix spam filtering capabilities are quite good, there are several methods to block spam in Postfix: access, access.cidr and main.cf.
Postfix access file
Add the spamming domain or IP to the file /etc/postfix/access. Also, you can add senders you accept at any conditions.
38.107.205.114 REJECTyahoo.com DEFER212.7.7.16 OKemailtkl.com REJECT
In Postfix access file the blank lines are OK, use # for comments. Read more: Postfix access
Postfix postmap command
After adding a new record to Postfix access file, rebuild the file with the command -
postmap /etc/postfix/access
Spam and Postfix
See also a more detailed article how to configure Postfix to fight spam - Configure Postfix anti spam
Additionally to postfix spam fighting tools you may want to install postgrey. Google for "greylisting wikipedia" or read this Killing that spam with greylisting using Postfix and Postgrey
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