Email Sender - Unable to send group emails

I am trying to send an email to a group email id like But the mail is not delivered to the users and snap does not show any error. I am able to send the same mail to individuals’ mail ids like What could be the issue?

I’m not aware of any issue. I send emails to groups over Gmail (business) daily.

Which email server are you using?

Thank you @dmiller.
It was a server configuration issue.