I am currently using the following rule: ufw allow out from my_local_ip to any port 587 This is a little too lax for my liking. I would like to tighten it up and restrict it to only gmail's smtp server ip addresses, but they are always changing. I used to just wait until an outgoing email didn't make it to its destination, then check syslog for the ip address that was blocked, then add that to the ufw configure script. However, now I have a need for much more reliability. Is there any way to use smtp.gmail.com in ufw? I don't think so, but thought I would ask. Any other ideas? Thanks.