Update 11/13/2023: We added new information on how to know when this change is released to your organization.
Today, we are announcing an update to our requirements for SMTP relay through Exchange ...
Updated Feb 22, 2024
Version 19.0
Blog Post
Hi Carolyn_Liu, many thanks for the response.
For some reason I can't sign-in as the username I setup yesterday (owainwt) so have had to re-register as this account.
"Is your accepted domain an InternalRelay type? If so have you checked MatchSubdomain in the accepted domain config? If so that's why it is working and you will be fine."
The accepted domain is marked as Authoritative, it is our tenant root domain, so there is no option to check MatchSubdomain.
The accepted domain it is our tenant root domain (tenantroot.com) and we have some systems sending emails using their system names to make a sub domain of our tenant root domain (server01.tenantroot.com).
Checking the header for one of these sub domain emails shows:
- Mail from/Return-path (P1) = server01.tenantroot.com
- From/Sender (P2) = server01.tenantroot.com
Both the P1 and P2 domains are a sub domain of the accepted domain (tenantroot.com).
As the P1 domain is not an explicit accepted domain (we do not have any sub domains registered) does this mean that 1.b under the New Requirements will not be meet or is the matching relaxed and hence it will work?
It's work now even though the sub domains are not accepted domains and hence would not satisfy either 1.b or 1.c under the Current Requirements, this suggests that the matching is relax?
Also, these sub domain emails are being sent to internal recipients only and all recipient email addresses are for the accepted domain (tenantroot.com), does this make a difference, is the impact related to external recipients only?
We can't change the accepted domain type of out tenant root domain so will the above scenario still work after the change?
"We will also publish a new property in MessageTrace in the near future, this property will tell you if the mail is using 1.c to accept the mail. Then you can tell exactly you are impacted or not."
These sub domain sent emails don't technically satisfy either 1.b or 1.c under the Current Requirements if the domain matching is strict - see above.
If the domain matching is relaxed they satisfy both.
Do you have a date for when this new property will be available?
Best regards
Owain