FYI, I believe I've mentioned this elsewhere, but I don't know where.... so in case you didn't see it before, I wanted to pass along a little tip.
Other m-bag organizers and myself have found it quite useful to create and maintain a shared list of books expected and/or received for the m-bag. In the past, I've used
Backpack, but Zoho (who we use for the Owed Books DB) also has a
Planner which allows you to make checkmark-type lists as well. (And it uses the same Zoho ID you're already using for the Owed Books DB.)
By having a list of what you're expecting, you can tell at a glance if there's anything still outstanding that you were waiting to receive, it's easier to post a list here later when you're getting ready to close simply by copying it over, and also the recipientwho might lose track of what they have coming to themcan see at a glance if it's a book waiting in their m-bag.
If you're also planning to accept BookMooch requests on behalf of the user, it's also useful there so they can add titles they've mooched and if they arrive and you're not sure what they're for, you have a list you can check against.