Name: Your Name (Whatever you want)
Email: Your email address is your username
Password: Your sent.as account password
Description: sent.as
Click Next Button
Hostname: imap.fastmail.com
Username: Your email address is your username
Password: Your sent.as account password
Hostname: smtp.fastmail.com
Username: Your email address is your username
Password: Your sent.as account password
Click Save Button
Use SSL: Yes
Authentication: Password
Server Port: 993
Use SSL: Yes
Authentication: Password
Server Port: 587