postgrey - 1.36-5.2 main

This package provides a policy server for Postfix to implement "greylisting".
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Greylisting is a spam filtering method that rejects email from external
servers on the first try. Spammers don't usually retry sending their
messages, whereas legitimate mail servers do.
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While Postgrey is designed for use with Postfix, it can also be used
with Exim.