Office 365 message encryption logic

[SB V]

Hi Community,

One of the customer would like to understand the Office 365 message encryption logic while the senders domain/license is unavailable after the message is sent.

Scenario:

Sender : User A from Office 365 - Message encryption is enabled.

Recipient : User B from Gmail

User A sends the email message to User B

User B encrypt the message by entering onetime passcode.

Things working fine

Now, Office 365 tenant is decommissioned, licenses are removed.

Questions:

1. Will User B still be able to decrypt the previous message sent by User A who was from decommissioned Office 365 tenant?

2. Will User B require onetime decryption or have to decrypt every time while they open the message?

Any guidance about the logic would be of great help.

Many thanks in advance!

[#2 · Accepted solution]

If the tenant has been deprovisioned (this can take a little time after licenses have expired), any previously encrypted messages will be rendered unopenable.

[#3]

Hi Vasil, Thank you very much for your inputs.

One another question is that

User B in this case needs to save the received emails for a period of 10 years as an example, Again, User A the sender, decommissioned their O365 tenant a while back.

How they can save or decrypt the emails to apply the retention rules for 10 years for legal reasons?

[#4]

They cannot, that's kind of the point for having them encrypted in the first place.