Our employees have huge folder structures within their Exchange mailboxes. Due to legal requirements in our sector, we have to utilize extremely rigid archiving solutions for all emails sent/received. Over the last 10 years, one member of staff has amassed 5146 folders, and close to 200,000 emails in a mailbox (the overall size is 2.6GB).

They have recently started experience strange glitches using both Outlook and webmail, where emails disappear (whole folders are shown as empty, when we know for a fact they are not - the providers (Rackspace) also confirm they can see emails in those folders when looking on the server).

I then discovered the Outlook 500 folder limitation (although the same issues occur in webmail). The providers are currently investigating the issue, but I'm trying to source solutions to consider in the meantime.

Has anyone else experienced this behaviour for large mailbox structure?

Can anyone recommend a solution where we can perhaps move the folders into a seperate file that is online (OST), so we don't have to manually back up many PST files per user?

  • Do you mean to backup just the folder structure, without actual emails and other items in them? – thims Aug 28 '17 at 17:28
  • No, I mean backup everything, even if that means moving the data out of the user's mailbox to reduce its size. – EvilDr Aug 28 '17 at 19:59
  • @EvilDr have you found a solution how to get around of the 500 folder limit? – Dominic Jonas Nov 22 '18 at 8:34
  • We migrated from Rackspace to Microsoft 365 and switched on Exchange Online Archiving for Exchange Online in the portal. Currently however we haven't uploaded all the archive files with all of the folders, so only about 40% of data exists at Microsoft. However, so far there's been no problems, although I don't hold out much hope of a cure when we migrate fully... It is a rediculous and archaic limitation. – EvilDr Nov 22 '18 at 12:54

That depends on your MS Exchange version & construct and if you are willing to pay less or more (or try to find a cost free solution).

So out of the blue:

And if you already using a hosted Exchange, move to Office 365 (Exchange Online) and then directly Exchange Online Archiving (EOA). You can choose a Office 365 plan here which included EOA (check here).

P.S. The biggest mailboxes I have are around 25 GB. Not optimal but I haven´t seen such issues you described. I also try to force the users to keep a local yearly archive and then keep that read only. Some users put a copy from the archive also on a fileshare and we will store that on one from our 10 year tape backups. Not optimal but works.

  • Thanks. I've asked Rackspace if they provide in-place archiving, and am waiting a response. I suppose EOA is only available if you're using Office 365 (you cannot archive to EOA from an existing Exchange online provided via a different provider)? – EvilDr Aug 29 '17 at 8:08
  • I do not know there environment but you can use a on premise Exchange (and there might be on premise but maybe one dedicated environment for you, or they use the exchange hosting mode) so it might be possible fro them to add EOA. However if you are half way in the Exchange cloud, so later one might decide not to use there service and move fully into the cloud. So they might not support EOA. [Oh and please accept this answer here or at least upvote it if helpfull for you] – BastianW Aug 29 '17 at 8:36
  • After a LONG period of research, we've migrated to Office365 and purchased the Microsoft Archiving for Exchange Online service. – EvilDr Oct 11 '17 at 9:31

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