Step Wise Manual Gmu mail settings for thunderbird
If you don't have a Gmu mail address. you can create an email id from here then you can Gmu email login.
Open Thunderbird Software App. Click on Email
When you click on the email, pop-up Set UP an Existing Account Screen.
Enter Your name, Gmu Email address and Password then press Continue.
Click on the Manual config menu at bottom.
Enter Below Gmu incoming server settings.
In incoming click on the dropdown menu and select IMAP.
Add server host :mail.gmu.edu
Port: 993
select SSL/TLS
Enter Below Gmu outgoing server settings.
In outgoing select SMTP.
Add server host :smtp.gmu.edu
Port: 587
select SSL/TLS
Tap on Done. Now you are ready to use your Gmu email account on your Thunderbird.