Convert an email into link from text in PHP

function.php

$string = 'please contact me on email@emaildomain.com';
ereg_replace("[_A-Za-z0-9-]+(\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\.[A-Za-z0-9-]+)*(\.[A-Za-z]{2,3})", "<a href=\"mailto:\\0\">\\0</a>", $string);

ereg_replace is deprecated therefore we can use:

function convertEmailToLinks($string) {
    return preg_replace("/[_A-Za-z0-9-]+(\.[_A-Za-z0-9-]+)*@[A-Za-z0-9-]+(\.[A-Za-z0-9-]+)*(\.[A-Za-z]{2,3})/", "<a href=\"mailto:\\0\">\\0</a>", $string);
}

text

Automatically converts into a link, since ereg_replace() is deprecated in PHP 5.3 we could use preg_replace

Now you can use above function like below:
echo convertEmailToLinks($string);

And output will be:
please contact me on <a href="mailto:email@emaildomain.com">email@emaildomain.com</a>