When you are "giving your address to the public" -- you are typically only doing so with the intention of receiving responses for a limited period. If you think about it, when you fill in a form you typically only wish to receive replies immediately, not three months later. The same applies to the Usenet: when you post an article you are only really interested in replies prior to the article's expiry.
This is where the concept of Temporary Addresses comes in. Mailtraq now supports the concept of an e-mail address that has an explicit expiry in it.
Explicit temporary addresses
Explicit addresses take the form username$E20120523@domain.com where the 20120523 is the explicit expiry date (yyyymmdd, or the 23rd of May, 2012).
If Mailtraq receives a message for an address in this format (at one of the local domains) it first verifies that the explicit date has not yet passed. If it has, it acts as though the address is in the Recipient Barring list and rejects it. Otherwise, it strips off the $E20120523 part and allows the message to pass.
Using Temporary Addresses
You can use the Explicit Temporary Addresses anywhere you have to give an e-mail address (such as in web forms).
The other form of temporary address is the Concealed Address