Ben Finney wrote: > Steve Holden <[EMAIL PROTECTED]> writes: > > > Ben Finney wrote: > > > The best advice I've seen when people ask "How do I validate > > > whether an email address is valid?" was "Try sending mail to it". > > > > > That only applies if it's a likely-looking email address. If someone > > asks me to send mail to "splurge.!#$%*&[EMAIL PROTECTED]><{}_)" I will > > probably assume that it isn't worth my time trying. > > You, as a human, can possibly make that decision, if you don't care > about turning away someone who *does* have such an email address. How > can an algorithm do so? There are many valid email addresses that look > as bizarre as the example you gave. > > > > The sending system's mail transport agent, not regular > > > expressions, determines which part is the domain to send the mail > > > to. > > > > > > The domain name system, not regular expressions, determines what > > > domains are valid, and what host should receive mail for that > > > domain. > > > > > > Most especially, the receiving mail system, not regular > > > expressions, determines what local-parts are valid. > > > > > Nevertheless, I am *not* going to try delivery to (for example) a > > non-local address that doesn't contain an "at@ sign. > > Would you try delivery to an email address that contains two or more > "@" symbols? If not, you will be denying delivery to valid RFC2821 > addresses. > > This is, of course, something you're entitled to do. But you've then > consciously chosen not to use "is the email address valid?" as your > criterion, and the original request for such validation becomes moot. >
What proportion of deliverable e-mail addresses have more than one @ in them? It may be a good idea, if the supplier of the e-mail address is a human and is on-line, to run a plausibility check -- does it look like the vast majority of addresses? Sure, "[EMAIL PROTECTED]@[EMAIL PROTECTED]" may be valid and deliverable, but "[EMAIL PROTECTED]@pastetwice.unorg" may be valid and undeliverable. IMHO a quick "Please check and confirm" dialogue would be warranted. Cheers, John -- http://mail.python.org/mailman/listinfo/python-list