Thanks folks. You all have very valid points. I always think I don't have enough knowledge to help answer questions, but by this point we probably do indeed have something to give back to the forum.
Our store knows because when we batch ship using Stamps.com, it automatically feeds back all the shipping information, like this:
"Shipped on 11/09/2013 via USPS [uSPS Intl Priority], Tracking number CJ4833XXXXXUS"
And adds it to the comments field. But the customer does not get an email. Seems like we just need to have the switch toggled to send it.
THIS. Exactly the part in bold. Also the database/file idea is something we had not thought about.
Will explore this add on.
Thanks - you guys are GOOD!!