I have a user that is trying to save an email message in outlook 365 connected to exchange 2010 without cache mode. The email contains a trail of several replies and attachments resulting in the size being 990KB

When they try to save the message to their desktop or a network share the operation fails with the error "there is not enough memory available to perform the operation"

So far searching has pointed to https://support.microsoft.com/en-ie/help/2968387/you-receive-insufficient-memory-errors-when-you-expand-a-mailbox-or-pu

But this isn't a match for the users configuration.

I've also tried increasing the page file size but this hasn't resolved the issue either.

I can't find a limit to saving an email in Outlook/Exchange, and appreciate if anyone who has come across this issue previously can share their solution.

Edit. Appears to be an issue with the size of the attached outlook items. The user in question has been sent a mail with 33 attached outlook mail items, and six documents as separate attachments. I can reproduce the error, but with a higher number of smaller attached outlook mail items, 50 in my case and the same number document attachments.


I have found that outlook 365 are not supported for exchange 2010, here's a microsoft official article for your reference: Clientsenter image description here

  • There is over 100GB free space on the users local disk, and plenty more than that on the network share, so space isn't an issue. Tried running outlook in safe mode and reinstalled but does not resolve the error. – NewExAdmin Aug 21 '20 at 8:59
  • I have found that outlook 365 client are not supported for exchange 2010, which is mentioned in this microsoft article: docs.microsoft.com/en-us/exchange/plan-and-deploy/… – Joy Zhang Aug 24 '20 at 7:24
  • We actually have support from MS until recently and are planning on upgrading exchange soon anyway. I've edited the question to give the latest findings appears to be an issue with the number/size of attached outlook mail items – NewExAdmin Aug 25 '20 at 8:45
  • Specifies the maximum size of a single attachment in a message. The message might contain many smaller attachments that greatly increase its overall size. However, the attachment size limit applies only to the size of an individual attachment. While you can't limit the number of attachments on a message, you can use the maximum message size limit to control the maximum total of attachments on the message. For more details: docs.microsoft.com/en-us/exchange/mail-flow/… – Joy Zhang Aug 26 '20 at 6:35

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