Head to the Settings icon and locate the Accounts & Passwords option.
Then select ‘Add Account’.
Select Other from this list.
iOS email menu

Select Add Mail Account.
iOS Add mail account

Input the information requested:
Name: Anything
Email: example@yourdomain.com
Password: Mailbox Password
Description: Work, Business…etc

iOS New email account

IMAP:

Incoming Mail Server
Host Name: imap.stackmail.com
Username: example@yourdomain.com
Password: Mailbox Password

Outgoing Mail Server
Host Name: smtp.stackmail.com
Username: example@yourdomain.com
Password: Mailbox Password

iOS email settings IMAP and POP

Finally, select the mail account and go into the Outgoing Mail Server settings. Select Primary Server, make sure SSL is switched on and the port is set to 587.