Email Repositories Routing at Google

If mail routing is needed for a LBL-authoritative subdomain's recipients to an on-premises email repository, then the owner(s) of that repositories need to take steps in order to ensure SMTP traffic for their domain(s) routes to their repositories once MX records have been configured to use Google's MX servers: https://support.google.com/a/answer/174125

Email Repository Owner actions:

1. Note the (host name or IP address) of the email repository
2. Note the lbl.gov subdomain that recipient addresses are using
3. Configure any firewall(s) to allow SMTP directly from Gmail's IP addresses (https://support.google.com/a/answer/60764)
   • The LBL border will be opened to allow port 25 (SMTP) from Gmail's IP addresses to all confirmed Email repository IP addresses

Once the above actions are confirmed, the Email team will:

1. Configure routes at Google from each in-use domain to its corresponding, confirmed Email repository IP address
2. Change MX records for Email repositories to Gmail's MX records: https://support.google.com/a/answer/174125