Your iPhone's settings might alter how you receive and send email messages. To optimize your email experience, adjust your "Optonline email settings for outlook." Tap Settings > Mail> Account Name to see your email account's settings. You may configure "Optonline email settings for Outlook" by entering the required account login, with server settings such as POP and IMAP. Outlook will be set up to store, send, and receive emails from the Optonline address you supplied after you finish the procedures successfully.
Optonline email settings for outlook