email address validation [duplicate]

Answer 1

Make an SMTP connection to the server, and do a 'Sender-Verify' lookup:

telnet <Yahoo MX> 25
helo here.com
mail from: here@there.com
rcpt to: asdfasdf@yahoo.com
data

You'll either get a code to proceed with transmission, or be given an recipient invalid message.

Answer 2

You could send an email to the address and have the user verify it by clicking on a link.

Answer 3

I hope the following document helps:

Validate an E-Mail Address with PHP, the Right Way

Answer 4

Most of the above answers look at regular expression check of email address. To actually see if the email address is valid you will need to connect to the SMTP server and send it commands. All details and PHP code is available here.

Use sparingly, Yahoo servers might block you if you send a lot of requests. Also it is highly recommended to use it along with the regular expressions as described by others.

Answer 5

Look up an MX record for that email address.

Answer 6

The only "propper" way to validate an email is to actually try to send an email to that address, but most times a regular expression will do the trick.

To complicate the issue, you might just want a simple validation like this

^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,6}$

or a somewhat more complex one like this

[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+(?:[A-Z]{2}|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum)\b

There is a pretty good article about email validation here