I have several school decks that I maintain, which are set to “private.” When I add a classmate to a deck (or multiple decks), AnkiHub will send them an automated link email. I also send them an email directly to let them know to check their spam folder, just in case. Sometimes people do not click through and then I later get emailed asking why the links don’t work.
How long are the links active in their email?
Alternatively, if there were a way for me to see who is subscribed and/or who still has a pending invitation, that would be really helpful.