Most throwaway e-mail services generate addresses using their clever domain name. Not ditchmail. The addresses ditchmail generates are never '@ditchmail.com'. It's a bad choice from a marketing angle but a plus for you.
Speaking of plusses, if you've ever tried using a "+" as an address extender for a gmail address, you probably ran into a site that rejected it. Sometimes it's due to a bad e-mail address validation algorithm. Sometimes the site owners are on to your clever "scam" and don't want you tagging your addresses for later filtering and tracing. Dashes are also out, because some very bad validators have problems with them too.
Ditchmail addresses use only letters, numbers, some dots, and an "at" symbol. No validator (even a really bad one) should have trouble with those.
A typical use of gmail "plus extensions" is to tag an e-mail address. Aside from the fact that bad validators often reject these, when you stick "+facebook" on your address, you're giving yourself away; it's obvious what your "real" e-mail address is. You also can't pack much information into a "+" extension.
With ditchmail, you can write, in plain language (or cryptically if you like), usage notes for your throwaway addresses that only you see. Each message you receive through ditchmail includes a preamble that can remind you why you used this particular address or who you gave it to in the first place. If a ditchmail address gets spammed, you know who sold you out (or maybe whose database got hacked).
Throwaway e-mail services usually have set expiration times, ranging anywhere from a few minutes to a few months. You choose the expiration date for each ditchmail address. And you can change that expiration date, or delete the address, any time you like.
Ditchmail began running privately in April 2004, and may finally open for public use in 2009.
Write to customer service rep Lynne Ochs at firstname.lastname@example.org if you would like a test account!