We continually add and remove IP's of servers that use the SMTP relay service and we do it manually, in the admin console. We've looked at the documentation, and we don't see any reference to setting these rules in the API. Is this possible to do?
Edit.- To do this in the console, you can folllow the procedure that is described in support.google.com/a/answer/2956491 (first step, point 8). – I haven't found any command to do it in the Admin SDK API. I don't know if there will be something else.