A GUID is a very large hexadecimal number that is nearly garanteed to be unique.
One example of a GUID is the following string:
D7D9B596-B50F-410A-A1B0-1211F8988986
This App can generate up to 999 such identifiers each time.
By touching the email button, the generated identifiers are compiled into an email message that is ready to be sent.