Invitation to outside my domain not receiving mail

1

When I invite users within my domain (eg. mydomain.com) everything is working fine, they were able to receive invitation mail.

But when I invite a user with an outside domain (eg. gmail.com/outlook.com) we’re not able to receive email.

2

I would check your SMTP options.

I.E. Microsoft O365 SMTP direct send does not allow for sending to external receipts outside of your domain.