Phillip from Emma Support here! I have taken a look around your account and it looks as if the issue is most likely because you have not added Emma to your SPF records, meaning that you have not given Emma (e2ma.net) permission to send for you. Once you add us as an authorized sender, it should help clear up the issue.
Since this issue is related to an internal sending, whitelisting Emma as a secure sender will help as well. Here are links to a few articles from the Emma Resource Center that will be useful for getting those SPF records up to date and whitelisting us for delivery. I hope they help clear the issue up and aid you in getting those invites to inboxes!