Settings as if they were for the iCloud account: example@icloud.com To use custom domain emails, use the same settings, usernames and passwords as below Just change the Email adress in the identity section (in thunderbird)
Server:
imap.mail.me.com
Port:
993
Conection security:
SSL/TLS
Username:
example
Password: Gernerate a app specific password from here
Server:
smtp.mail.me.com
Port:
587
Conection security:
STARTTLS
Username:
example
Password: use the same one that you generated earlier