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The gwhitelist script assists mail administrators in placing the google outbound SMTP servers on a Postfix postscreen whitelist. The output format can be changed easily to suit other purposes. Written for /bin/sh Bourne Shell.

It is presumed that the mail administrator already knows how to use Postfix's postscreen whitelisting facility.

The script generates a list of CIDR-formatted IP addresses from google's SPF records, and outputs the list to stdout in a format suitable for a postscreen CIDR lookup table.

Tested under OpenBSD 5.3, FreeBSD 9.1, and Debian GNU/Linux 6.0.6.

BSD license

Download gwhitelist 1.1 (2KB)


Update, July 30, 2016:

The recent availability of DNS-based IP whitelists has provided me with the whitelisting functionality and information that I need for my very low volume mail server, so I will not be updating gwhitelist in the future.

If you have the need to use gwhitelist-type functionality, I recommend you investigate Steve Jenkins' PostWhite, which has the functionality of gwhitelist, and more.

PostWhite is available here ( and here (

Thank you for your interest in gwhitelist.