I asked a slightly different question, how do I know if an invitation was sent or not sent. Maybe it’s such a case that without appreciating (it’s busy with some kind of problem), or the message will end up in the spam folder and will be deleted. How does the host know if it received the message or not ?. I am writing about such a case, is there another way to find out if the letter was sent or not? And if not about me, how long should I wait?
