Google IP address ranges for outbound SMTP

When you are configuring email handling for your domain, for example, seeking to prevent Google messages from being marked as spam, you might need to know the IP addresses of the G Suite mail servers.

Note: The following instructions are for listing IP addresses used for handling email traffic. This is not meant to be a complete list of Google-maintained IP addresses.

Google maintains a global infrastructure, which grows dynamically to accommodate increasing demand. As a result, G Suite mail servers use a large range of IP addresses, and the addresses often change. The most effective means of finding the current range of Google IP addresses is to query Google's SPF record.

To create an SPF record for your domain, you can simply have the record refer to the Google SPF record for the current list of IP addresses:

v=spf1 include:_spf.google.com ~all

With this method, your domain automatically inherits changes to the Google IP addresses as they happen.

When you need the literal IP addresses for G Suite mail servers, start by using one of the common DNS lookup commands (nslookup, dig, host) to retrieve the SPF records for the domain _spf.google.com, like so:

nslookup -q=TXT _spf.google.com 8.8.8.8

This returns a list of the domains included in Google's SPF record, such as:
_netblocks.google.com, _netblocks2.google.com, _netblocks3.google.com

Now look up the DNS records associated with those domains, one at a time, like so:

nslookup -q=TXT _netblocks.google.com 8.8.8.8
nslookup -q=TXT _netblocks2.google.com 8.8.8.8
nslookup -q=TXT _netblocks3.google.com 8.8.8.8

The results of these commands contain the current range of addresses.