I wrote a regexp a little while ago that will validate an email pretty well. It allows for pretty much anything before the '@' except for whitespace and '@', then allows alphanumerics and hyphens in the domain name (with the same rule for n subdomains), then an alphabetical tld. I figured it would be a waste of time to maintain a list of all the tlds, so I just check to make sure the tld has two or 3 letters, or is 'info' or 'museum'.

/^[^@\s]+@([a-z0-9\-]+\.)+([a-z]{2,3}||info||museum)$/i
[download]

I would very much like to know if anyone can offer improvements on this, as I plan to use it again soon, but I've tried quite a number of garbage addresses and they're stopped. A limitation of this regexp is that characters like ';' and ',' are not stopped in the first part, so someone could theoretically send extra addresses -- but the '@' is stopped. So, someone could theoretically get your program to send mail to local accounts, or just generate errors. I felt this was an okay compromise, but to stop this you could change the regexp to:

/^[^@\s;,]+@([a-z0-9\-]+\.)+([a-z]{2,3}||info||museum)$/i
[download]

Of course, if you really want to validate the address, you could always do a DNS lookup on the domain name (don't laugh, I know people who've done it), but I can't think of any way to check if the address is valid...

LAI
:eof