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Just migrated some accounts from an on-prem Exchange server to O365. Some of those accounts need IMAP access. IMAP access is turned on for those individual mailboxes in the cloud Exchange control panel, but it's not working. Pointing the client at the outlook.office365.com server for IMAP just comes back with bad account/password on the e-mail client. Is there some other setting on O365 that needs to be turned on for IMAP to work? Username should just be the e-mail address, correct?

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  • Have you configured the account to use ssl and port 993 – Drifter104 Jan 24 '19 at 15:37
  • Do you have MFA enabled (as you should)? – Esa Jokinen Jan 24 '19 at 15:37
  • @Drifter104 Yes, it's setup for SSL and port 993 – Brian Knoblauch Jan 24 '19 at 15:48
  • @EsaJokinen Ah, good point. Yes, my account is setup for MFA, does that block IMAP then? I'll try turning MFA off to see if it makes a difference! – Brian Knoblauch Jan 24 '19 at 15:49
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You have multi-factor authentication (MFA) enabled. IMAP doesn't support MFA.

Your users need to create separate App Passwords for IMAP on https://account.activedirectory.windowsazure.com/AppPasswords.aspx

This would probably have worked without enabling IMAP for individual users.

By default, POP3 and IMAP4 are enabled for all users in Exchange Online. You can disable them for individual users.

To be complete, you also need correct IMAP & SMTP settings:

  • IMAP: outlook.office365.com:993 using TLS
  • SMTP submission: smtp.office365.com:587 using STARTTLS
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  • Thank you so much! Solves my problem perfectly. I've been battling this for days and nowhere in any of the documentation I've read have I found anything about MFA changing how IMAP passwords work! – Brian Knoblauch Jan 24 '19 at 18:08
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From Microsoft 365 admin center find necessary user-> disable 'Authenticated SMTP' option, save and after 3-5 minutes enable again and save: see picture

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