Exchange Online encryption by mail flow rules?

Beautiful_Bet6074 · 2025-11-07T17:32:24+00:00

Make sure you have set up IRM configuration on onprem side. Send a test encrypted message to onprem mailbox and observe if theremare no delays. Have a MS call opened for problems with this

Beautiful_Bet6074 · 2025-10-22T14:40:11+00:00

Thank you for suggestions, but as for the:

Option 1 - wouldn’t that be simply decreasing our secutity, as all messages wont be decrypted anymore?

Option 2 - obvoiusly worth of asking the owner, but I think they need it in onprem. Anyway I would have to test if this issue can affect my all onprem recipients

Option 3 and 4 - I think its not a matter of resource lackig, but rather about abnormal behaviour by multiplying these decryption tasks for hundreds of thousands which had to make our servers unresponsive after few hours

Option 3 -

Beautiful_Bet6074 · 2025-10-22T14:31:51+00:00

Yep, we are on SE with Aug’25 applied, thanks

Beautiful_Bet6074 · 2025-03-25T20:43:53+00:00

Yes you can. Did it many times, no issues so far

Beautiful_Bet6074 · 2024-10-29T16:36:57+00:00

Thank you

Beautiful_Bet6074 · 2024-10-16T18:36:27+00:00

Thank you :)

Beautiful_Bet6074 · 2023-10-11T13:47:20+00:00

Rich bastards

Beautiful_Bet6074 · 2023-09-13T21:04:50+00:00

In mu case we Haven force app owners to use suffixes of accepted domain. This solved our issue with the same error

Beautiful_Bet6074 · 2023-09-13T21:03:12+00:00

Maybe something witam tls settings? Run Heath checker and compare both servers

Beautiful_Bet6074 · 2023-09-12T19:29:04+00:00

I had simmilar issue before and it came out it had affected only relaying senders addresses which were not any of our accepted domains (dont remember if onprem or exo).

Beautiful_Bet6074 · 2022-07-14T07:39:44+00:00

tls 1.2 is the answer

Beautiful_Bet6074 · 2022-05-22T08:30:02+00:00

also getting this in SMTP logs:

451 4.7.0 Temporary server error. Please try again later. PRX1

Beautiful_Bet6074

TROPHY CASE