I require a function that will test the validity of an email address, submitted by browsers to my mailing list. My thoughts on stages of validation are as follows, but open to input.
1. Extract domain name from value, and confirm A-Record and MX-Record exists.
2. Query SMTP server and see if username or mailbox exists, returning errors as required.
3. Finally extract user, domain name and TLD sections from email which can be checked against know problem domains. ( Checking domain code is already done, but extraction is required).
1) Complete and fully-functional source code of all work done.
2) Exclusive and complete copyrights to all work purchased. (No GPL, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site).
Apache for Windows [url removed, login to view], PHP 4.3.2