Outlook changes recipients randomly after clicking on Send Button

Question

Outlook changes recipients randomly after clicking on Send Button

Anonymous

Since Monday, January 9th we have a very weird behavior on random users. Appointments or mail are sent to different recipients than intended. Sorry, if this gets long, but it's complicated and as severe as it could get.

We have ~1100 users. There are already ~10 cases from which I know as they had severe impact. There are probably some minor cases that users didn't report.

Example 1

A secretary updated the already sent out monthly meeting to our partners with hotel dates etc. There is an explicit distribution list for these partners.

Then she suddenly got an answer of 2 people who were never invited and taken off of the partners list 1 year ago. They asked why they got invited. As I checked, they were both in the CC line of the appointment. The secretary definitely did not take them there. We could see in former update mails that the two wrong "partners" weren't invited. It was only in this update.

I sorted it to a kind of unexplainable error with possible user mistake then.

Example 2

2 colleagues sent out mail to a group of people. Both completely independant and at different times. But while sending Outlook added a distribution list to the whole company (1100 recipients!) to the CC line. They claimed the mail back.

I witnessed one of the incidents, but as no one called me after that I sorted this also as a kind of user mistake, but was already attended and had an eye on it.

Example 3

This finally proofed that there is a technical thing going wrong in Outlook/Exchange Online. A user sent an appointment to a specific customer (external mail). But instead of him the same distribution list (whole company, 1100 recipients) as in Example 2 was used and everyone in the company got the appointment. And of course a cancellation, when she realized, what happened. She already called me while I was realizing the problem. So I could finally be present and directly see what she's doing.

I could not believe what I saw: She took the right adress from the suggestions Outlook makes. We checked with a double click on the recipient, the adress shown there was correct.

But after sending and checking Sent Objects folder we directly saw it changed to the distribution list. Of course we cancelled it then again.

To suspend problems with the Outlook profile I immedately created a new one for her. From that moment we only worked in the new profile. But the third and final try to get this appointment out, the same happened as above. Weird.

As she knew the customer already, she phoned him and he never received anything from her that day. That's important at the end of the case.

After some troubleshooting I found that when addressing a normal e-mail and typing the first few letters, she only got the correct suggestion for the customer. Doing the same in the appointment, after few letters she got the same suggestion on top of the list, but already some other entries. These were beginning with the same letters, but still consistent concerning name and e-mail address. Then the weird thing happened which got me nearer to the reason of the problem: Having typed the whole mail adress of the customer before the @-sign, suddenly some stupid suggestions appeared.

Normally correct suggestions are formatted like that:

First line - name or complete mail address of the recipient

Second line (smaller) - the concrete mail address of the recipient

So a correct suggestion in our case would be:

******@soul.com

******@soul.com

But these suggestions were all different:

******@soul.com

******@soul.com

******@soul.com

******@soul.com

******@soul.com

******@ourcompany.com

******@soul.com

******@ourcompany.com

Then we started to delete these entries one after another, until ~25 as strange as the above were all deleted. So no suggestion came, she then typed the whole adress by hand.

This was the first time the appointment reached the customer! And was not sent to anyone else.

Today she called me again, the same thing happened again to "James Brown". When she checked the suggestions, she got:

******@soul.com

******@soul.com

Fact: She never had James Brown in her contacts. Only as recipient in some mail or appointments. Like the other suggestions. So Outlook still does this.

Example 4

A colleague in my department sent a simple application for leave to a Shared Mailbox. But instead of the SMB it was sent to a team distribution list (luck, it was his own team). It also worked only correctly when he deleted the suggestions.

Final information

This all started last week and there are more similar examples, but the above should do it.

I assume it has to do with the 2021 feature where Outlook got a kind of AI that connects contact entries. Could it be this feature was upgraded to do this in the address suggestions? I find nothing related in the Release Notes.

How can we take this off?

One can imagine, that this is a kind of time bomb, as every day something really evil could happen (confidential info reaching 1000+ recipients). You cannot be sure now, if an intended recipient really gets the mail alone, or other uninvolved people get it accidentally.

We use Office version 2208. All users use Exchange Online. There is a Hybrid configuration (1 Exchange 2016 on-premise only for Active Directory).

2 answers

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Answer 1

ChristyZhang-MSFT 26,126 Microsoft External Staff

Hi @Anonymous ,

Welcome to our forum!

Does this issue occur in Web mail?

So no suggestion came, she then typed the whole adress by hand. This was the first time the appointment reached the customer! And was not sent to anyone else.

According to you description, I notice that the issue disappeared when the user typed the recipient' address. So I'm afraid that the issue is related to the corrupted Auto-Complete List. When you clear all suggested addresses and use the suggested addresses again, does the problem recur?

If the issue disappears, please first make sure you have upgraded your Outlook to the latest version. And then clear all entries from the Auto-Complete List for each user with problem.

Hope to help you!

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ChristyZhang-MSFT 26,126 Reputation points Microsoft External Staff

2023-01-19T08:53:16.3466667+00:00

Hi @Widescreen ,

Thanks for your reply!

At this time we can't tell what is causing this problem, the first thing is that we need to clear this corrupted list. For your concerns, we can try two methods to troubleshoot:

1.In order to avoid the interference of Outlook add-ins and other programs, it's suggested to close other programs temporarily and restart your Outlook in safe mode to check if the issue has any differences(Windows + R> type "outlook.exe /safe">enter).

2.Considering that it may be caused by the damage of the profile/data file in the Outlook client, it is suggested that you could try to create a new profile(Control Panel>Mail>Show Profiles>add) and add the account for testing to check if there are some differences.

If Outlook does that (what I proved) how can this be turned off?

Do you want to turn off the Auto-Complete List? If so, please follow the below steps:
Anonymous

2023-01-19T08:54:24.7066667+00:00

Hi @ChristyZhang-MSFT ,

First of all, thanks for trying to help me.

All the information you asked for is in my text (sorry again for the length).

No, all users are using Outlook for Windows. As stated we use 2208, but it already occured some days before we upgraded to it from the last release. This is the newest release we have in our release channel (Semi-Annual Enterprise).

The issue did NOT disappear, when the user typed in the address. My text says, that AFTER we deleted all wrong AutoComplete entries she typed the whole address (as there was no suggestion anymore, of course) and THEN it reached the right recipient for the first time.

The problem is not a single corrupted AutoComplete List at very few users. The problem ist that this does not solve it permanently and could happen again a day after a fresh deletion of the list. The more important question is, how can such a "corruption" be prevented as it happens again and again at random users? If it corrupts that often it must be a kind of design failure.

And how could it be explained that this started to happen concentrated after Jan 9th, but never before?

How can it be possible that the AutoComplete List repeatedly connects addresses with totally different addresses without any interaction of the user? Why does it connect anything? What would be the benefit of that? It's enough to suggest formerly used addresses, send to the one intended and nowhere else.

If Outlook does that (what I proved) how can this be turned off? This is an everyday risk of severe violation of privacy protection, if you cannot be sure who gets your mail, even 1000s of people. If every single mail you write could possibly get public.
Anonymous

2023-01-19T09:46:02.2833333+00:00

Oh, nice. You answered my last comment 1 minute before I sent it. :-)

So this forum doesn't convert local times and therefore mixes up the comment order. :-/

To 1.

It doesn't help, if I just set 3 test users to Safe Mode. As I cannot predict which users would be affected next and WHEN, how should this work? Turn 1000+ users to Safe Mode? For how long? And what if the problem does not appear then? How do we know that it wouldn't have appeared without Safe Mode? The last 24 hours there was no problem.

Perhaps we should try 500 users in Safe mode, 500 not? And see, if the latter have problems, the others not?

You see, this is very difficult. :-)

But thanks for pointing to Add-Ins, I will check them again as possible interference.

To 2.

"To suspend problems with the Outlook profile I immedately created a new one for her. From that moment we only worked in the new profile. But the third and final try to get this appointment out, the same happened as above. Weird."

My statement in the inital question. So I can already say, this doesn't help. Might lead to a feature not depending to local Outlook only but to be performed after the mail has left the local client.

We already consider to deactivate AutoComplete. I think this could be the way to prevent further damage for a short time. But I know that many people rely on the simple (former kind of) AutoComplete as their main resource for daily mail. So that kind of hard cut-off of such a basic feature should not last very long.

So, can you confirm that this is already investigated at Microsoft? Do we get an update here if there are any findings?
ChristyZhang-MSFT 26,126 Reputation points Microsoft External Staff

2023-01-27T09:07:34.29+00:00

Hi @Widescreen ,

Thanks for your reply!

According to your description, i notice that the issue doesn't occur when you started Outlook in Safe mode and earlier after creating a new profile, right?

If so, considering that it has only been up and running normally for a while in the new Profile, to further confirm if the problem is related to your current Outlook program, please try to uninstall and reinstall Office to check if the problem persists. If the problem persists, I'm afraid some third-party software on your current computer is affecting Outlook. It is recommended that you could try to perform a clean boot for windows and check if the issue still occur.

Answer 2

Oskar Shon 866

I can say that is a solution to send emails for 100-1000 recipients separately using my Outlook addin.

That is a easy proces and no more mistakes using autocomplete list with have only 100 addresses in memory.

Also if you have more complicate email addresses multi-membered, what Outlook can't handle I can recommend this solution, or others to get addresses directly from incoming or outcoming messages.

Regards

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Outlook changes recipients randomly after clicking on Send Button

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