Outlook 365 Message Encryption not working for some Exchange 2019 on premise users

Question

Outlook 365 Message Encryption not working for some Exchange 2019 on premise users

Chan, Richard (Singapore - SG) 0

hi, our org has a hybrid model with Exchange 2019 on premise for mailbox, and Azure/Entra ID for cloud apps like Teams/Sharepoint. All of us has M365 E3 Enterprise License

we are exploring using the "Encrypt" option in Outlook, but there are differing behavior

some users are able to send the Encrypt -> Do Not Forward option without errors
myself and another colleague encountered the following error when trying to do the same
One of the IT colleague was able to send the email, but the recipients cannot open the email.
All of us (except our managers) are unable to open the encrypted email
Does the encryption also applies to attachments like emails, to prevent users from opening the attached email and forwarding?

ChristyZhang-MSFT 26,221 Reputation points Microsoft External Staff

2024-04-01T07:42:55.44+00:00

Hi @Chan, Richard (Singapore - SG) ,

Welcome to our forum!

Does this issue occur recently? If so, have you done any specific operations before that?

And in order to further confirm the issue is related to Outlook desktop client, it's suggested that you could log in to your web mail and do the same test to check if there're any differences.

In addition, Do Not Forward option can work with some users, please check if there're any differences between the users with and without problems, just like permission, or if the computer is AD joined, etc.
Chan, Richard (Singapore - SG) 0 Reputation points

2024-04-01T08:34:33.6+00:00

thanks Christy for the prompt reply.

we just started exploring the Encrypt feature recently, so we are trying to find out what caused the different behavior as our users are using Outlook 365 apps for Enterprise. The computers are all joined to AD, and on the same E3 license. Are there any permissions that I need to check?

On OWA, we do not see the Encrypt - DNF option, only the following
ChristyZhang-MSFT 26,221 Reputation points Microsoft External Staff

2024-04-02T07:16:10.23+00:00

Hi @Chan, Richard (Singapore - SG) ,

Create a new email and check here:
Chan, Richard (Singapore - SG) 0 Reputation points

2024-04-02T07:19:57.5266667+00:00

hi Christy, our OWA is Exchange 2019 (on premise), so the options are different from our Office 365 Outlook desktop client.

We can see the Encrypt -> Do not Forward option only in our Outlook desktop client. However, not everyone can send or open the encrypted email
ChristyZhang-MSFT 26,221 Reputation points Microsoft External Staff

2024-04-02T07:32:40.24+00:00

Hi @Chan, Richard (Singapore - SG) ,

The screenshot i provided is from OWA via New email>Options>Encrypt.
Chan, Richard (Singapore - SG) 0 Reputation points

2024-04-02T09:23:32.75+00:00

Thank you @ChristyZhang-MSFT , our OWA is running Exchange 2019, and there's no Encrypt option as shown
Chan, Richard (Singapore - SG) 0 Reputation points

2024-04-03T04:16:05.9833333+00:00

hi @ChristyZhang-MSFT does the Encrypt button works with Exchange 2019 users? do we need to configure the Azure RMS for all users for the Encrypt function to work?

it's very weird as some users were able to use the feature, but majority could not
ChristyZhang-MSFT 26,221 Reputation points Microsoft External Staff

2024-04-24T05:56:40.58+00:00

Hi @Chan, Richard (Singapore - SG) ,

Thanks for your reply!

Considering that the issue is related to some users, in order to confirm if the issue is related to Outlook desktop client, it's suggested that you could add the account of the user who is experiencing the problem to Outlook for the user who is not experiencing the problem and check if the problem persists.