Outlook Client Weirdness

[Techie-Tech]

Good morning,

 

We are having strange issues with the Outlook client for users that have access to more than 1 mailbox.

 

For example, the PA to the Head has access to her own account, a shared mailbox specifically for PA emails and also access to the Heads email account. The accounts are listed on the LHS of the Outlook client and all the emails can be seen etc

 

When attempting to send an email from Outlook as either the shared PA account or the Heads account, she gets the 'You do not have permission to send the message on behalf of the specified user'.

 

If she uses OWA (where we have added these accounts under FOLDERS, all works fine.

 

Anyone got any ideas as to what's going on here as I've not come across this issue before.

 

We're using Microsoft® Outlook® for Microsoft 365 MSO (Version 2302 Build 16.0.16130.20806) 64-bit

 

 

 

Thanks in anticipation!

[akidosaint]

I would check whether the head has permission to PA personal mailbox. Had something similar where person A and Person B had access to each others mailbox and automapping threw some similar errors

[snagrat]

We have the same issue. Looks like Outlook Client is trying to send on behalf of now rather than SendAs.

If you open OWA it works OK, so the permissions are OK.

 

Did you get anywhere troubleshooting the root cause?

 

We are running 2309 but only started Monday.

Edited December 5, 2023 by snagrat

[evasion]

Same issue here. think that root cause is that Outlook cannot enumerate GAL anymore. When "sending as" from shared mailbox, you have to go to to search for your shared mailbox account clicking 2x on From button, and refresh that way, otherwise you get error as seen above. Giving "send on behalf" permissions does not help. Because GAL search works fine in OWA, it can be workaround for while until root cause is fixed. And the root cause is in Outlook client, not being able to resolve GAL search anymore. Instead having to go for offline address book is not a solution, because your default online GAL must be up to date before it syncs with offline version. It's like your offline address book is now more up to date, which is weird.

For some reason new version of Outlook client (slide toggle button in upper right corner) will resolve GAL search better and be able to send as, from shared mailbox, but the shared mailbox is no longer available in left pane in new Outlook. Adding new account (shared mailbox, delegated to "send as") will fail.

Reverted to old version because new one is just like half baked cake. Nice looking cosmetically, but lacking in functionality. Not to mention that email profile adjustments in control panel don't work with new version.

Edited December 6, 2023 by evasion

[snagrat]

For me it was changes to the GAL meaning the account being sent as was not available. Fixing that sorted the SendAs

[evasion]

I don't know how this can be fixed, if GAL search no longer works as intended. It still has the same "pre canned" filter (catch all) which is supposed to find shared mailbox which exists in offline address book, down on the list under GAL.

[Techie-Tech]

We have the same issue. Looks like Outlook Client is trying to send on behalf of now rather than SendAs.

If you open OWA it works OK, so the permissions are OK.

Did you get anywhere troubleshooting the root cause?

We are running 2309 but only started Monday.

 

Still having the issues here.

 

Have downloaded the address book and the only thing that fixed was being able to edit the calendars for the other mailbox, but still cannot send mail.

 

This is infuriating!

[evasion]

Yes, root cause is that GAL search scope in Outlook client is now limited to only one address book. And yet search filter in default GAL is not changed, search just stopped working Monday for no apparent reason.

[evasion]

What a surprise this morning, "send as" works fine just as it used to before this glitch last week. GAL search also works fine as it did before. Something got fixed in exchange online in the meantime, maybe it took longer for power shell command to apply GAL update.

[evasion]

At long last, with some help from Microsoft, I have a solution to this specific "send as" issue.

As described here, I only had to change this registry value (Office 365):

 

Windows Registry Editor Version 5.00

 

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Profiles\Outlook\0a0d020000000000c000000000000046]

 

"00033d1b"=hex:00,00,00,00

 

 

which changes Address Book to "Custom", and as a result everyone can now send from delegated mailbox or shared mailbox, no problems.

 

If, this setting is reverted to "01 00 00 00" which enables Start with Global Address List, then "send as" no longer works as intended.

 

It only took 3 months to arrive to this simple fix. Why Outlook behaves in this way, I have no idea.

 

No need to switch to new outlook or use web mail as workaround.

Edited March 26, 2024 by evasion