Graywall is a program that adds a graylist (or greylist) feature to the Mercury/32 SMTP server. It uses the Mercury/32 API facility that has been introduced in version 4.51. You must have at least this version of Mercury/32 to run Graywall!

Information about graylisting in general can be found at: We recommend that you read this first.

The basic features of Graywall are as follows:

  • It accepts some incoming SMTP sessions and rejects others according to certain conditions.
  • Authorized connections, or connections from specified IP addresses, are not affected by Graywall.
  • Graywall is compatible with the sending of SMTP mail by server farms.
  • Graywall is compatible with the “reverse delivery test” used by some systems as an anti-spam test (for example,
  • Servers which successfully pass mail through are whitelisted by Graywall for the specific mail domain, and subsequent messages are not delayed by Graywall.
  • Support for whilelisting of incompatible servers by external file. See:

License, support and donations

You can download:

en/graywall.txt · Last modified: 2009/06/06 10:25 by geby
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