How It Works:
When you send a postcard, you create a file on the server with a filename
reflecting the date and time it was created, i.e. "xhhmmss_mmddyynnn.html"
(the x is a random digit, and the nnn is a checksum). An e-mail
notification is then sent to the recipient, telling him or her to look at
that file. When he or she reads the postcard, that file is added to
a list of cards to be deleted that night at midnight. So, if you receive a
postcard, you can view it as many times as you want that day,
before it is removed permanently from the system. You can save the card
for future use by selecting "Save As" from the File menu. If the recipient
does not read the postcard, it is kept on the system for one month
before it is automatically deleted.