Use these steps to know how do I set up my AT&T email on my Mac device:
From the mail, choose mail > preferences.
Now, choose accounts and then tap to + sign.
After that, choose to add another mail account and then tap to continue.
Complete to add a mail account info like full name as you want to display to others, AT&T email address, and next is to enter the password or secure mail key.
After that, choose to create, and the account will automatically configure and appear in the account list.
Lastly, close the preferences Windows to use the email account smoothly.
Verify or update AT&T email settings
Already have your email set up, but want to update your settings or add your secure mail key? Here’s what you have to do:
Select Preferences > Account Information.
Choose your mail account.
Select POP3 or IMAP.
Confirm User name.
Enter your password or secure mail key.
Confirm or enter the following settings:
Incoming Mail Server - inbound.att.net (POP3) or imap.mail.att.net (IMAP)
Outgoing Mail Server - outbound.att.net (POP3) or smtp.mail.att.net (IMAP)
In Outgoing Mail Server (SMTP), choose Edit SMTP Server List.
Server Name - outbound.att.net or smtp.mail.att.net.
Use default ports - 25, 465.
Use Secure Sockets Layer (SSL) is selected.
On Advanced tab, confirm:
SSL checkbox is selected.
Authentication field is set for Password.