How can one append information in an Excel spreadsheet to a barcod

I work at a post office and we have come up with a system that will use
barcodes on each mail receptacle that when scanned call up customer email
addresses, placing them into the spreadsheet so that they can be copied and
pasted into Outllook to notify customers when they have mail. We have all of
the email addresses in the spreadsheet, but I'm not sure how to append them
to the barcodes on the boxes so that when scanned, the corresponding email
address is entered into a spreadsheet and then the cursor moves down to the
next line. I have some programming experience in VB and JAVA so if Macro
functionality is what is needed to accomplish this task just point me in the
right direction and I can figure the coding out myself. Thanks to anyone for
any help!