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IMAP4 Connection Limits RRS feed

  • Question

  • I have an Exchange 2010 SP3 server and another Linux server running Fetchmail which uses IMAP to connect to Exchange every minuted to pull email. Fetchmail is randomly have errors connecting. My current theory is that Exchange has some kind of limit for IMAP as far as number of connections in a set amount of time. However when I look at connection limits in the EMC they all look sufficient. I'm wondering if there are limits set somewhere in the registry that are no displayed in the EMC that I would need to change to correct the issue.

    So far Outlook and other clients show no issues connecting with IMAP, but I have two Linux servers with Fetchmail that are having this issue.

    Vincent Sprague

    Wednesday, July 11, 2018 2:33 PM

All replies

  • Hi,

    Do you configure connection limitation by IMAP setting? Run below command to check:
    Get-ImapSettings | FL Max*

    Also, it might be limited by throttling policy, you can run below command to check:
    Get-ThrottlingPolicy | FL IMAP*
    Figure as below:
    image

    More information, for your reference: Exchange 2010 Client Access Throttling

    Best Regards,
    Allen Wang


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    Thursday, July 12, 2018 6:15 AM
  • When I run Get-ImapSettings | FL Max* it shows me this:

    MaxCommandSize            : 10240
    MaxConnections            : 2000
    MaxConnectionFromSingleIP : 2000
    MaxConnectionsPerUser     : 32

    This also matches what I see in the EMC.

    When I run Get-ThrottlingPolicy | FL IMAP* it shows the IMAP entries and they are all blank.

    Both of my CAS servers return the same information. Yet, Fetchmail appears to work fine one the older CAS server (SP1) but not the newer (SP3) server.


    Vincent Sprague


    • Edited by Baron164 Thursday, July 12, 2018 4:01 PM
    Thursday, July 12, 2018 3:59 PM
  • For testing, we can set them to Unlimited for Throttling Policy.

    Also, check the Application log by Event Viewer to find more information.

    Best Regards,
    Allen Wang


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.


    Click here to learn more. Visit the dedicated forum to share, explore and talk to experts about Microsoft Teams.

    Friday, July 13, 2018 1:37 AM
  • Hi Baron164,

    Any update now?
    If the above suggestion helps, please be free to mark it as answer for helping more people.

    Regards,

    Kyle Xu


    Please remember to mark the replies as answers if they helped. If you have feedback for TechNet Subscriber Support, contact tnsf@microsoft.com.

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    Monday, July 23, 2018 5:55 AM
  • MaxConnectionsPerUser defines how many connections user can make during throttling policy interval (240 seconds):

    https://ficilitydotnet.wordpress.com/2013/10/10/imap-connection-settings-and-workload-management-on-exchange-2013/

    Wednesday, August 14, 2019 1:59 PM