What are the Google and Postini IP ranges?

This Help Center article is for Postini, a suite of Google services that are now discontinued. If you're searching for instructions related to Google Apps, see the Google Apps Help Center. For instructions related to Google Apps Vault, see the Vault Help Center.

Important: In preparation for the Postini Transition to Google Apps, Postini customers must ensure that their firewall allows both Google and Postini IP address ranges. If you configured your firewall a long time ago, it may be open to Postini IPs but not yet to Google IPs. (If you never locked down your firewall in the first place, you may not need to make changes to your firewall configuration.) See How your firewall should be configured for more details.

Locking down your firewall to Google IP address ranges

For instructions, see Google IP address ranges.

Locking down your firewall to Postini IP address ranges

The following are the IP ranges for the Postini systems:

System IP Range CIDR Range IP/Subnet Mask Pair
5, 6, 7, 8, 20 -
9 -
10 -


11, 20, 200, 201 -

Note: For System 20 customers, two sets of IP ranges are applicable.

To determine the Postini system for your account:

Your system number is shown the URL when you log in to the Administration Console or Message Center. The system number is prefaced by "ac-s" or "mc-s", for example:

URL displayed for an account on System 8 when logged in to the Administration Console:


URL displayed for an account on System 200 when logged in to the Message Center:


Note: As of September 2004, the following IP ranges are no longer in use. It is safe to remove any mail server or router configurations to accept traffic from these ranges without impairing the email protection service connectivity. ( mask ( mask ( mask ( mask ( mask ( mask ( mask ( mask ( mask

For a checklist of security best practices and links to other important resources for your service, visit Postini Security Central.
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