Nasty Bug Lurking In Outlook For Years. The Trigger. Any Fix Or Workaround?

[Chuck Davis]

Operating system::    Windows 11
Outlook version:     (Classic) Outlook
Email type or host:    Microsoft 365, Outlook.com

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My wife and I use (Classic) Outlook via Microsoft 365. We both have multiple email accounts in Outlook. (My wife has two accounts, I have five.) There are no Shared mailboxes.

One of my wife's e-mail accounts is <name>@Outlook.com and the other is <name>@<domain>.com, hosted on an Exchange Server at GoDaddy.

Two days ago my wife became unable to send messages. She would get a rejection message from the System Administrator. It was a long, detailed message but the core was: "/o=ExchangeLabs/ou=Exchange Administrative Group" "You do not have the permission to send the message on behalf of the specified user". She could send emails using OWA and (as determined later) (New) Outlook.

If you search Google using these two search terms you will find that many people have reported the same error going back at least 3-4 years. Despite many threads with Microsoft "Support", it appears nobody could find a cause or a fix.

I keep stash copies of our Outlook Profiles, but switching to one of these backup Profiles did not fix the problem.

I uninstalled/reinstalled Outlook several times, with no success.

I found one thread that stated the root cause was having two (or more) email accounts combined with a problem with the Global Address List. I confirmed this by removing one of the accounts from my wife's Outlook config, after which sending worked fine. I tried the Global Address List repair procedure suggested in the thread, but it blew an error.

My wife's (Classic) Outlook, with two email accounts, had been working fine for years. Just before this error began I made a temporary change to her configuration, re-linking to an Archive.PST file that had accidentally been moved to a different location. Apparently touching the configuration opened the door to this error. (And just to make things more interesting..........my wife's PC is around a year old. My PC is a month old. For both PC's I did a from-scratch installation of (Classic) Outlook, with multiple email accounts, without any problems.)

I currently have my wife running on (New) Outlook, but I definitely am a member of the "New Outlook Sucks" chorus.

I am now totally paranoid about touching any part of the (Classic) Outlook configuration on my PC.

Is anybody on this forum familiar with this error and, hopefully, a fix?

Does anybody know how to repair or replace the Global Address List?

I have daily (Macrium) image backups of our systems going back 30 days. Does anybody know of any files or executables that I could restore that might fix this problem? (Reminder - I have already done several uninstalls/reinstalls and have tried using backup Profiles.) I believe that the Global Access List may reside on the MS365 Exchange Server, placing it out of reach.

Thanks.

 

[Chuck Davis]

Update - Attempting to access the Global Address List on both of our PC's, using either (Classic) Outlook or OWA, throws an error. (As far as I know, but can't see, the GAL is empty.)

 

[Chuck Davis]

Update 2 (Unable to edit OP or first comment) - Attempting to access *any* of the Outlook.com Global Address Lists on *both* of our PC's using (Classic) Outlook *or* (New) Outlook *or* OWA blows an error. The GAL for my wife's <name>@<domain>.com hosted at GoDaddy is accessible.

On my wife's PC I deleted the .OAB files from AppData. Only one of them, presumably from GoDaddy, was recreated when I restarted (Classic) Outlook.

It appears that all of our GAL files on the MS365 Exchange Server are corrupted, with no way to repair or replace them.

This only appears to cause a problem in (Classic) Outlook, however, when there are (exactly?) two email accounts and (apparently) a change is made to a Profile. (I'm not willing to experiment on my PC by changing my Profile.) The (probably) corrupted Outlook.com GAL's don't break (New) Outlook or OWA, even though the GAL's are not accessible from (New) Outlook or OWA.

Any suggestions would be extremely welcome. All I can think to try at this point, after some sleep, is to restore the .OAB files from the Macrium backup to AppData.

 

[Diane Poremsky]

It's a bug with outlook.com and Microsoft 365 accounts are in classic Outlook and Microsoft is investigating
Classic Outlook error when sending from Outlook.com "You do not have permission to send on behalf of the specified user." - Microsoft Support

re-linking to an Archive.PST file that had accidentally been moved to a different location. Apparently touching the configuration opened the door to this error. (And just to make things more interesting.

That shouldn't cause a problem unless she is replying to mail in the PST and is using the 'wrong' account.

ETA: You probably should wait to delete the offline address book - but it's not harmful if you do decide to delete it. If the problem is caused by the issue in the article and the admin hides the GAL entry then definitely download the offline address book (or delete the files) to clear it.

Update 2 (Unable to edit OP or first comment) - Attempting to access *any* of the Outlook.com Global Address Lists on *both* of our PC's using (Classic) Outlook *or* (New) Outlook *or* OWA blows an error. The GAL for my wife's <name>@<domain>.com hosted at GoDaddy is accessible.

Outlook.com is hosted on exchange so it has a single member gal (only has the user's address) but it's useless and should be ignored - Microsoft can't hide or remove it.

I would delete the GAL files in C:\Users\%username%\AppData\Local\Microsoft\Outlook\Offline Address Books - there should be 2 folders there. Delete both.

Then, if you want to, you can redownload the GAL - Send/Receive tab > Send /Receive Groups > Download Address Book... This is not necessary as Outlook will eventually resync it. But if she needs it for work before it syncs on it's own, you'll need to sync it. (She should only need it if she has a shared mailbox and it now has permission errors - Outlook gets the permissions from the offline gal.)

 

[Chuck Davis]

Thanks for your quick response, Diane.

I was encouraged when I saw multiple posts about this error spanning at least 3-4 years. I was discouraged when I discovered that none of the posts provided a solution or workaround. I was encouraged when I went to the Microsoft Support article that you linked above. I was discouraged when I saw that the article had last been updated in February 2024 and that there was not yet a solution.

The Microsoft Support article states: The issue may happen more consistently if the Outlook.com account is in an Outlook Profile with another Exchange account. The issue only affects sending email, receiving email continues to work as expected.

This matches my wife's situation. She has an Outlook.com account and a <domain>.com account in her Profile.

I believe that the root cause is that all of our Outlook.com GAL files are corrupted (or unusable for some reason). As noted above, any attempt to access or download any of the Outlook.com GAL's, using (Classic) Outlook, (New) Outlook or OWA blows an error. This also makes any of the workaround suggestions that involve manually downloading a GAL impossible.

Apparently this is harmless unless and until a change is made to a Profile. This apparently triggers a download of the GAL's, which fails for the Outlook.com accounts, leading to the inability to send e-mails from (Classic) Outlook (but not (New) Outlook or OWA).

I stepped through the daily Macrium backups. Both sets of .OAB files were present up until the day I changed my wife's Profile. The .OAB files were dated in 2023 and 2024. After I "touched" the Profile, the .OAB folders and files were missing.

If you have a contact at Microsoft, and if Microsoft is investing any effort into (Classic) Outlook, you might suggest that they look upstream to see why all of the GAL's are corrupted or otherwise unusable. I would be happy to give them access to our accounts. At the least, they could make (Classic) Outlook able to ignore the resulting missing .OAB files in the same way that (New) Outlook and OWA are able to.

(For folks with this issue that find this thread, the Microsoft Support article implies that a possible workaround would be to set up separate Profiles for the Outlook.com and <domain>.com accounts and switch between them. My wife decided that this was too cumbersome, so we didn't experiment with this and she is going to try and endure using (New) Outlook. This might be something to try, however.)

 

[Diane Poremsky]

The date is either wrong or it was updated recently - (pretty sure its wrong) as its at the top of the Feb 2025 list -

Fixes or workarounds for recent issues in classic Outlook for Windows - Microsoft Support

support.microsoft.com

a possible workaround would be to set up separate Profiles for the Outlook.com and <domain>.com accounts and switch between them. My wife decided that this was too cumbersome, so we

Yes... too cumbersome. Using one account in classic and one in new Outlook is better.

 

[Diane Poremsky]

As an FYI... the date should be fixed soon. It is an emerging issue and a dev is actively working on it. Fingers crossed it won't take long to figure it out and fix it.

 

[Chuck Davis]

Thanks. I sent MS a link to this thread via the Outlook Feedback channel. Hope springs eternal.

 

[Chuck Davis]

Some additional information just to keep everything in one place.

This bug is apparently also breaking API's or embedded routines that send messages via Outlook.com. My wife and I use Macrium to back up our PC's to our NAS. Macrium is one of the most widely used backup products.

As soon as (Classic) Outlook "broke" on my wife's PC, messaging from Macrium was also partially broken. Sending a test message from Macrium, via Outlook.com, still works. Success/Warning/Failure messages stopped working however. This indicates that whatever the problem is, it is effecting programs outside of (Classic) Outlook.

I don't know how this embedded code works, but I suspect the problem also goes back to the corrupted/unusable GAL's that can't be downloaded, combined with code that may or may not ignore the failed download. What's not visible is how this could be related to having an Outlook.com and <domain>.com account in a Profile.

 

[Diane Poremsky]

Sending a test message from Macrium, via Outlook.com, still works. Success/Warning/Failure messages stopped working however. This indicates that whatever the problem is, it is effecting programs outside of (Classic) Outlook.

That indicates it's a problem with the MAPI API.

What's not visible is how this could be related to having an Outlook.com and <domain>.com account in a Profile.

If the cause is the MAPI API, its not related to the GAL.

 

[Freelancers]

A long-standing bug in Outlook causes issues with multiple accounts. The trigger isn't always clear, but it may involve account syncing or sending from the wrong default account.

Possible Fixes/Workarounds:

1. Check Default Account – Ensure the correct default account is set under File > Account Settings > Email.
2. Create Separate Profiles – Use different Outlook profiles for each account.
3. Update Outlook – Ensure you have the latest version installed.
4. Use Cached Mode – Enable it under Account Settings > Change > Use Cached Exchange Mode.
5. Repair Office – Go to Control Panel > Programs > Microsoft 365 > Repair.

 

[Chuck Davis]

A long-standing bug in Outlook causes issues with multiple accounts. The trigger isn't always clear, but it may involve account syncing or sending from the wrong default account.

Possible Fixes/Workarounds:

1. Check Default Account – Ensure the correct default account is set under File > Account Settings > Email.
2. Create Separate Profiles – Use different Outlook profiles for each account.
3. Update Outlook – Ensure you have the latest version installed.
4. Use Cached Mode – Enable it under Account Settings > Change > Use Cached Exchange Mode.
5. Repair Office – Go to Control Panel > Programs > Microsoft 365 > Repair.

All but #2 checked and/or done multiple times. As noted above, #2 is not an acceptable workaround.