[TooTall52]

This won't work accurately as many email servers out there accept all mail, process it then kick back bounces for the invalid ones. microsoft exchange works this way for example, may Lotus Notes as well.

so just because a helo passes does not mean it is valid address, the seperate pop account is probably more accurate.

TooTall52

Originally Posted by fatal1980

You dont send a "HELLO" email message. You just connect to the SMTP server for the domain name and send some regular SMTP commands to verify if the email exists.

Ill show you how it can be done manually.

Find the MX record

[comm@taco:/home/comm]> dig hotmail.com mx

;; ANSWER SECTION:
hotmail.com. 3600 IN MX 5 mx4.hotmail.com.
hotmail.com. 3600 IN MX 5 mx1.hotmail.com.
hotmail.com. 3600 IN MX 5 mx3.hotmail.com.
hotmail.com. 3600 IN MX 5 mx2.hotmail.com.

Connect the the one of the MX records (I've *** out my email address):

[comm@taco:/home/comm]> telnet mx2.hotmail.com 25
Trying 65.54.245.40...
Connected to mx2.hotmail.com.
Escape character is '^]'.
220 bay0-mc10-f11.bay0.hotmail.com Sending unsolicited commercial or bulk e-mail to Microsoft's computer network is prohibited. Other restrictions are found at http://privacy.msn.com/Anti-spam/. Violations will result in use of equipment located in California and other states. Fri, 22 Aug 2008 19:53:02 -0700
HELO test.example.com
250 bay0-mc10-f11.bay0.hotmail.com (3.6.0.91) Hello [64.40.106.55]
MAIL FROM: j***@gmail.com
250 j****@gmail.com....Sender OK
RCPT TO: n*****@hotmail.com
250 n****@hotmail.com
DATA
354 Start mail input; end with <CRLF>.<CRLF>
^]
telnet> Connection closed.

As you can see the mail was accepted after the DATA command. So this was successful.

Now lets see one thats failed on an address that didn't exist.

[comm@taco:/home/comm]> telnet mx2.hotmail.com 25
Trying 65.54.244.168...
Connected to mx2.hotmail.com.
Escape character is '^]'.
220 bay0-mc6-f8.bay0.hotmail.com Sending unsolicited commercial or bulk e-mail to Microsoft's computer network is prohibited. Other restrictions are found at http://privacy.msn.com/Anti-spam/. Violations will result in use of equipment located in California and other states. Fri, 22 Aug 2008 19:56:44 -0700
helo test.example.com
250 bay0-mc6-f8.bay0.hotmail.com (3.6.0.91) Hello [64.40.106.55]
MAIL FROM: ****@gmail.com
250 *****@gmail.com....Sender OK
RCPT TO: badmail1231233123@hotmail.com
550 Requested action not taken: mailbox unavailable
^]
telnet> Connection closed.

As you can see the SMTP session fails! Easy test and you don't need to send a message to the server or process bounce messages. This is the same process used in the following module that works very well:

https://vborg.vbsupport.ru/showthread.php?t=144590

Your wasting your time and resources on use a POP3 account, just use the above method. While your at it you can also re-create the above module for 3.7 since it hasn't been coded over to 3.7 and it would be fairly easy.