Clear mail address from a synchronized Security Group after deleting it in on-prem AD
Let's say you have a security group with email address, firstname.lastname@example.org, on AAD that is synchronized from on-prem AD.
Delete the email address in on-prem AD, and run a sync. The SG now has email address of email@example.com.
IMHO, the email address should be completely deleted from the SG on AAD too.