Re: Email verification (was: [PHP] Removing Invalid Users)

> "Steve Werby" <steve-lists@befriend.com> writes: > > Like Tom said, use regex to check the email is of a valid format. A small > > percentage of servers can be contacted to find whether an email address is > > valid, but fewer and fewer are allowing this so it's completely unreliable. "Arcady Genkin" <a.genkin@utoronto.ca> wrote: > There's a nifty little open source program called `vrfy' which does > nice things about email veryfication. Finding it is left as an It is a cool tool, but like I said in my email most servers won't allow you to test email address validity. It's possible using the command VRFY or the even more dangerous EXPN to determine whether an email address is valid or in the case of EXPN to expand an alias to return a list of all recipients. It's a good idea to disable these commands on the server so spammers can't easily determine valid email addresses, malicious folks can't get a list of all of your employee email addresses and hackers can't determine valid usernames to attack the server with. FYI, in sendmail both commands can be disabled by making sure PrivacyOptions is set as follows: PrivacyOptions=noexpn novrfy Or you can set them to the following which goes a little further: PrivacyOptions=goaway So unfortunately vrfy will only be useful when checking servers that haven't disabled that command. :-( -- Steve Werby President, Befriend Internet Services LLC http://www.befriend.com/