Hi NCVA,
As I understand it, you cannot send emails to everyone in a distribution group because of the 500 recipients limitation.
Given the situation, I’d like to clarify whether the distribution group is stored in your mailbox’ Contacts folder. For distribution groups stored in the Contacts folder of a mailbox, the members of the group are counted individually. For distribution groups stored in the Global Address List (shared address book ), the group is counted as one recipient.
Thanks,
Maggie Li