On Purim, I will drive around and deliver my mishloach manot. However, if a person is not home, I might leave the package at his door. If he doesn't arrive until days later, have I still satisfied my obligation to send because I delivered it to his door on the right day? Does it matter if I know that he is not (or will not be) home?
If I know he isn't home on Ta'anit Esther, can I leave it at his door then, knowing that he won't get home until it is properly Purim, so the actual receiving of it will be on Purim. Could I leave it a week early (or longer) if I know he won't be around until Purim?
This last one just popped into my head and might need a separate question -- I don't know the rules of conditions well enough. If I am visiting a friend on Ta'anit Esther and I won't see him on Purim, can I put a package in his house and say "I am placing this here but not transferring ownership of it to you until tomorrow"? Could I do that on the day before the fast with a longer conditional period?