How do I connect to my mailbox using IMAP?

HUIT does not recommend using IMAP or POP to connect to your Office 365 Outlook mailbox. Email clients that are configured via IMAP will experience a variety of limitations, security and performance issues. These issues include:

  • Loss messages due to data throttling  which occurs when you are attempting to move mail. Throttling is controlled by Microsoft and cannot be changed, adjusted, or removed

  • Most system message flags and all custom flags are not supported. Only the "Read/unread" and "Important" flags are available.

  • If your email client is configured via IMAP, Outlook Web App will show drafts and duplicates of messages you've already sent.

However, if you do decide to configure your client via IMAP, the below suggestions may help mitigate some of the performance issues.

  • Do not sync all folders locally if you have a large mailbox. Throttling will occur and slow down your email system and email application.

  • Frequently compact, or archive your mailbox, especially if you have a large mailbox.

Sometimes, using IMAP or POP is unavoidable. For those cases, connection details are as follows:

    • IMAP4:, port 993 (SSL)
    • POP3:, port 995 (SSL)
    • SMTP:, port 587 (TLS)