Verify if an email address exists.

[Alex Dean]

On Sep 8, 2010, at 12:22 AM, Dan Dubovik wrote:

> If you want to know if a specific email address is available, you  
> can try to send an email to the address, and note the response code  
> after sending it.  Using php, you can use the mail() function,  
> however, the error message it returns is binary in nature, either it  
> sends or not, without a real reason why it failed to send.

That tells you if PHP was able to hand the message off to the local  
MTA (sendmail/postfix/etc).  It doesn't give any indication of whether  
the destination address is valid or not, unfortunately.

Keith: The only sure way I know of to tell if an address is valid or  
not is to send a 'please reply to this message' email, and see if you  
get a response or not.  And (as mentioned by others) that's not a  
guarantee that the address you sent to is actually the address which  
the email was delivered to.  Aliases, catch-all accounts, etc can all  
play a part.

alex