Update iOS Mail Server Settings

Getting to the Mail settings

1. Go to the Settings application.
2. Choose Passwords & Accounts.
3. Select the email account in question. 
4. Select the top option Account followed by the email address.

Incoming Mail Server

5. Ensure the 'Host Name' is imap.stackmail.com
6. Ensure the 'Username' is your full email address.
7. Ensure your 'Password' is entered correctly. 

Outgoing Mail Server

8. Select the SMTP option beneath the 'Outgoing Mail Server' heading. 
9. Click the option underneath the 'Primary Server' heading which should be a server address followed by On >
10. Ensure the 'Host Name' is smtp.stackmail.com 
11. Ensure the 'Username' is your full email address.
12. Ensure your 'Password' is entered correctly. 
13. 'Use SSL' should be on (green).
14. 'Authentication' should be Password.
15. 'Server Port' should be 587. 

Saving the Settings

16. When that is all correct select Done in the top right corner. 
17. Click Account in the top left corner.
18. Click Done in the top right corner. 
19. Then navigate back to the mail app and attempt to send and receive emails.