FIX: Change email from to not have via site_name for group SMTP (PR #13788)

We now use the group’s full name in group SMTP emails, so we are dropping the via #{site_name}. If group owners still want this they can just change the full name of the group.


Is it safe to remove :email_from or something else is still using it??

We still use it for regular non-group-smtp emails so we have to keep it.