Not receiving email invite

[rduffy73]

I'm a premium family subscriber, I joined Spotify with a Facebook login. I invited my wife and son to join my family plan. My son (on Gmail) received the invite and got on my plan no problem. My wife (who also joined Spotify with a Facebook login) has not recieved any of the join emails I've tried sending her. How can I fix this? I've read people tell others "just send her a manual join email." I have no idea how to do this. Any help would be appriciated. Thank you all.