Where can I change outgoing ports for email accounts?

In Mail Preferences/Accounts/Account Information, click on the arrows beside the name of the SMTP -- is the box to use this SMTP only checked?

After clicking on the arrows, select Edit Server List -- under the first tab the server and name should be listed. Then if you click on the Advanced tab, you will see the Port selection mechanism. If you know the port it should always use, you may want to select Use Custom Port and enter that number, and PW, Username if required.

Ernie

My outgoing email just stopped working.

If it was working and nothing changed on your computer or router, the most likely scenario is something changed (broke maybe) with your ISP.

😉

A couple of things to check :

Is another email client working fine ?
Are you using your ISP's SMTP server ?

If multiple accounts are configured, near the From menu when you compose a mail, there is a menu to choose the SMTP server, is this one consistant with the server you are trying to use ?

As asked earlier, is "only use this server" checked for that account ?