The welcome message gets some prepended text if the new user came to the forum by way of an invitation. There’s a minor typo in there - see screenshot. But the real issue for me is that this template text is not editable by admins. It’s very good already but I think admins will want to customize it a bit.
I also do think the message should come from the inviter or at least the inviter should be included as a recipient in the PM, and the inviter should be given an opportunity to write a brief personal message to the invitee.
