Connection Settings for POP/IMAP Mail Client in Office 365 Exchange Online

Posted on Updated on

exchange_online_banner_sm  Hi all, as you may be using POP or IMAP clients within Office 365 Exchange Online, you may have found that your mail client was initially not able to connect into your EXO mailbox.

In researching this issue I have found that EXO, using the namespace AND Hotmail, also using the same namespace, are conflicting and causing EXO MBX users to be provided with the following connection settings for their email client, thus sending the user to the Consumer Messaging endpoints instead of EXO.

  1. is configured to send to  The mail client connects to this endpoint and receives the following connection string(s) from the service, instructing the mail client application where and how to connect.
    1. Autodiscover connection settings received
      1. 995 or

Note – When using these settings, your client will receive the following error and the client cannot properly connect into the EXO MBX.



  1. Click the Manual Config link and change the IMAP and SMTP connection string(s) and click Done
    1. Note the namespace for Incoming and for Outgoing connection settings/strings.


Once the above has been completed and the Done button clicked, you will notice the mail client connections and begins the process of downloading email!


Note – Special thanks to those who helped me diagnose this issue and quickly come up with a manual workaround for this issue. I am working with Operations to help identify how to split Hotmail and EXO from using the same namespace, allowing users to receive the correct autodiscover connection settings, so they will not need to perform this Manual Configuration, as outlined above.

Note – Apparently this is already a known issue and is addressed in this article.  I am still working to discover whether Exchange Online can help differentiate the difference between Consumer versus Business namespaces, so these older mail clients can leverage the autodiscover connection settings being returned.  For now you will need to either follow these steps listed above or reference the official article:


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