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TonyRedmond's avatar
TonyRedmond
MVP
Dec 01, 2016

Outlook 2016 and its many connections to Office 365 Groups

If you examine the network connections opened by an Outlook 2016 client, you might find many connections established to the mailboxes belonging to Office 365 Groups. Using connections to grab data is...
Office 365 Groups
Mike Platvoet's avatar
Mike Platvoet
Steel Contributor
Dec 02, 2016
Great stuff Tony! I never noticed this. I work for large schools where we plan to deploy a whole bunch of groups based on other memberships (such as HR groups/teams, Project teams etc.) automatically. This may be something to keep an eye on. Thanks!!
  • VasilMichev's avatar
    VasilMichev
    MVP
    Dec 02, 2016

    I think the biggest concern around this is in situations where NAT is involved, as having that many open connections can easily cause port exhaustion. However, when I did the same test with 100 groups, quick check with netstat showed only a handful connections compared to normal Outlook usage, wile the Outlook Connections dialog was showing well over 100. The truth is somewhere in between I guess...

    • TonyRedmond's avatar
      TonyRedmond
      MVP
      Dec 02, 2016

      I suspect that some of these connections are used (to synchronize with a group) and then torn down after a period of inactivity in the group but they remain listed as active. On the other hand, some threads might reawake because some activity occurs in the group. There's no doubt that the picture presented by Outlook can overstate the real situation, but I shall leave it to the engineers to figure out.

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