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
Exchange Team Blog
4 MIN READ
Updated Requirements for SMTP Relay through Exchange Online
The_Exchange_Team
Jun 19, 2023Platinum Contributor
Carolyn_Liu
Microsoft
Jul 24, 2023Microsoft
Q1: Is a wildcard certificate necessary to satisfy the conditions below?
Any of the following is an accepted domain of your organization:
SMTP certificate domain on the SMTP connection; or
I have certificate of mail.test.com and Accepted Domain is test.com.
Then I wonder if the purchase of *.test.com is necessary?
Answer>> No, purchase wildcard certificate is not necessary. The easiest is to add mail.test.com as the accepted domain.
Q2: Do I need (1-a) Multiple SAN certificates to meet the same conditions? I have test1.com, test2.com, and test3.com as Accepted Domains.
But the certificate is only mail.test1.com.
Then, should test2.com and test3.com be included in the SAN to satisfy the condition below?
SMTP certificate domain on the SMTP connection; or
Answer>> condition 1 a/b/c are "Or" condition, meaning only one of them needs to be satisfied. Currently so long if one of a/b/c are satisfied, in the future, will be one of a/b needs to be satisfied. We are going to remove c.