> It performs a MX-lookup, which IMHO is the best way to check for validity.
But that's expensive and slow, and doesn't tell you whether the user
part of the address is valid (and in general, there's no way to
determine that short of actually sending a message). So what's the
point?
-Doug
That's why I think the better term for this is "well formed". "Validity" can only be determined by sending to it, but you can tell if an address at least conforms to the specs programmatically. In the end, when talking about a "valid" address in this context, that is what most people are talking about.
The point is to weed out malformed email addresses, just like you would enforce any other data formatting standards in other types of data.
