I had a look at this PHP SMTP Email Validation and found it pretty useful.
How would I be able to post results to a MySQL database,
the info posted to the screen wont help if you have 100's of thousands of email addresses to validate.
>>>
HELO example.com
<<<
250 user.example.com Hello example.com(74.52.107.82)
>>>
MAIL FROM: <noreply@example.com>
<<<
250 sender ok <noreply@example.com>
>>
RCPT TO: <user1@Nexample.com>
<<<
250 Recipient ok <user1@example.com>
>>>
RSET
A basic MySQL db could be like this;
CREATE TABLE `tblemail` (
`id` INT(3) NULL AUTO_INCREMENT,
`txtmail` VARCHAR(100) NULL,
`response` VARCHAR(20) NULL,
`valid` VARCHAR(1) NULL,
PRIMARY KEY (`id`)
)
COLLATE='latin1_swedish_ci'
ENGINE=MyISAM
ROW_FORMAT=DEFAULT