Error in Outlook client: Your message did not reach some or all of the intended recipients

Question

I have one user who constantly gets the error in the title. He tries sending an email, then receives an automated email from the System Administrator saying his was undeliverable with the following details:

This message could not be sent. Your server administrator has limited the number of items you can open simultaneously. Try closing messages you have opened or removing attachments and images from unsent messages you are composing. Try sending the message again later, or contact your network administrator.

 

Diagnostic information for administrators:

Error is [0x80040305-0x000004de-0x0000054a].

Submit-Message failed: message id(2), failure enum(6), HResult(0x80040305), EC(0).

He then must close Outlook and relaunch it and attempt to send the email again, which often will work.

Following some advice I found online, I tried turning off 'download shared folders' which appeared to resolve the issue for a couple of months, but it has recently started reoccurring and is worse than before (happening 5+ times a day).

He has no additional mailboxes that he uses. He has tried using a different laptop and the issue has followed him. I have checked the Event Viewer and no errors or warnings are coming up relating to Outlook or Exchange. I have asked him to try launching Outlook in Safe Mode and he says the behavior is the same. However it does not occur when he uses the web client. Creating a new profile in the Outlook client appears to provide very temporary relief.

I am at a loss! Any ideas out there?

Answer 1

Hi @Dan Hopper ，

Considering that the issue has followed the user in new Outlook profile and even a different laptop, I tend to assume it could be more related to the user's mailbox.

Does the user have a large number of folders in his mailbox?
Is the size of the mailbox way larger than the other users'?

If possible, you can try turning off Exchange cached mode and see if there would be any improvement in Online mode.

Additionally, below are links about some scenarios and possible solutions to performance issues in Outlook. You can take a look at them and see if anything can be applied to your situation.

• Outlook performance issues in a Cached Exchange Mode .ost or .pst file
• How to troubleshoot performance issues in Outlook

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Answer 2

Hi @Dan Hopper ，

What’ the version of your Exchange Server?
Any clues in the Event viewer on Exchange server when the error appears?

Please try keeping less data offline by adjusting the time frame via File > Account Settings > Account Settings, select the account, Change, then move the slider to less amount of time, such as 3 months or 1 month.

In case the issue persists, I'd suggest trying to increase the open item limit by following the steps in the link below:
(Important: Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.)
Managed Store Limits in Exchange Server

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Answer 3

It looks like it was a corrupted PST file. Here is the article for those curious: https://support.microsoft.com/en-gb/office/repair-outlook-data-files-pst-and-ost-25663bc3-11ec-4412-86c4-60458afc5253