seems like it would be quite useful for catching what you sent with actual outbox clients, but outbox is actually a second level of complexity above this, maybe you can build this out:
sometimes it may happen that your outbox capable client failed to send an event to your outbox relays, or, maybe you changed them, and messages that you sent would get missed
but your follow list contains a list of users, if you gathered their relay lists you could then make an extended search to catch the stray stuff that for whatever reason (ie, using a non-outbox client to publish a message, or relays down) you didn't find by looking at your outboxes
seaching your follows for their inboxes would give you a second phase to the process and then you would definitely catch the dregs at the end of the bottle
