[SOLVED] Third Level Domain Name in Email Address

We are having trouble adding a user who has a third level domain name in their email address, for example bob@third.second.org (‘org’ being the first level). Is there a simple fix to get around this? The error that the user is receiving states: “The email you provided does not belong to an accepted domain. Please contact your administrator or sign up with a different email.” But…I have already added users outside the accepted domain list by sending them an invitation, so I don’t think that this is the problem. Other than this one little issue, Mattermost is rocking it and we’re leaving Slack in the dust!
Cheers!
-Jeff

Thanks @jeffkn for the feedback, appreciate it!

What is your Restrict account creation to specified email domains set to? You can find it in System Console > Users and Teams > Restrict account creation to specified email domains

Thanks for the response! I just cleared out that section and resent the invite. We have other users from different domains already, but they might have been imported from another program. I was under the impression that was for users to sign themselves up if they had an email address with a domain name listed in that box. Thanks again!