For example, if you want to email technical support at wemightspam.com, you can create a dynamic address that will expire in 30 days. That way if they add you to their mailing list, it won't matter (after 30 days, at least).
If you want to by a book from wemightsellyourname.com, you can create a Dymamic Address that will be rejected if the sender's domain is not 'wemightsellyourname.com'.
They are a bit too long to actually print on a business card, and no one would want to type it in.
A simplified example might be if your email address was email@example.com, and you wanted an address that would expire on 2001/3/31, you could encode it as
The server recognizes the address as being dynamic (from the leading ..), and then can check the date, and reject the address if it has expired. Note that it doesn't accept the message, then bounce it, it immediately rejects it as it arrives, minimizing spammers impact on your system.
That's not the actual format, the format is a bit more complex, but that's the general idea. For implementation details, see com.worldware.DynamicAddress.java
There is no standard for Dynamic Addresses. As far as we know, they are completely original to Ichabod.
There is no need for Dynamic Addresses to be standardized. A mail server must be able to generate and recognizes its own Dynamic Addresses. Other mail servers an clients just use them as if the were normal addresses.
As long as the receiving mail server understands its own Dynamic Addresses, it doesn't matter if other servers use different implementations. In fact, we encourage different implementations. The more different implementations there are, the harder it will be for spammers to keep up.