We're using Office365 with Exchange Online.

One problem we have, is that we have one mailbox, that is set up for all our users in the local outlook of their local machine. So it gets saved to their .ost file. All business related e-mails like orders, offers, order confirmations etc. are received and sent from this mailbox.

This works quite ok, but there are two problems.

  • When a user is in holidays or absent, then comes back and starts his outlook after 14 days, it has to reload a ton of e-mails, making outlook unuseable for a couple of minutes, and also it takes away much of our companies bandwidth.
  • When the mailbox gets too full, we have to delete like 10'000 E-Mails, to make space. We can only do this on weekends, with all outlooks on all machines started, otherwise it would have to sync/reload the e-mails during office hours which again, would make Outlook unuseable.

I'm now thinking about either setting up a local (expensive!) Exchange 2019 Server to get rid of the problem, so that we don't sync from the cloud, but instead from the local exchange which should be quicker.

Is this the correct way to adress this problem? Is the only solution to set up a local Exchange server, or could I fix the problem without any changes? Would it make sense to do a Exchange Online / Exchange Server Hybrid?

Thank you very much


It seems the goal is to make Outlook more faster. I think you may first try some suggestions:

Try to turn on cache mode in Outlook client, it would create a local copy of the mailbox data in an offline data file (.ost file). This may help improve the performance of Outlook on slow Internet connections. https://support.office.com/en-us/article/turn-on-cached-exchange-mode-7885af08-9a60-4ec3-850a-e221c1ed0c1c

If the mailbox is too full, make users to archive the mails with local pst files to clean up space. https://support.office.com/en-us/article/archive-items-manually-ecf54f37-14d7-4ee3-a830-46a5c33274f6

  • thank you, but this won't help. we're using cached mode already, and making users archive the mails themselves is also not very nice. I also don't think it would go through without any problems. – SimonS Apr 16 '19 at 5:44
  • It seems Outlook would work for tons of mails. You could consider to increase the bandwidth, Exchange on-premise may be help, and I think it also depends on the client machine performance. – Shaw Apr 18 '19 at 9:11

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