Validate Email address in PHP

You can use the filter_var() function, which gives you a lot of handy validation and sanitization options.

filter_var($email, FILTER_VALIDATE_EMAIL)

• PHP Manual filter_var()
• Available in PHP >= 5.2.0

If you don't want to change your code that relied on your function, just do:

function isValidEmail($email){ 
    return filter_var($email, FILTER_VALIDATE_EMAIL);
}

Note: For other uses (where you need Regex), the deprecated ereg function family (POSIX Regex Functions) should be replaced by the preg family (PCRE Regex Functions). There are a small amount of differences, reading the Manual should suffice.

PHP 5.3.3 and 5.2.14 had a bug related to FILTER_VALIDATE_EMAIL, which resulted in segfault when validating large values. Simple and safe workaround for this is using strlen() before filter_var(). I'm not sure about 5.3.4 final, but it is written that some 5.3.4-snapshot versions also were affected.

This bug has already been fixed.

This method will of course validate bazmega@kapa as a valid email address, because in fact it is a valid email address. But most of the time on the Internet, you also want the email address to have a TLD: bazmega@kapa.com. As suggested in this blog post, you can augment filter_var() with a regex that will check for the existence of a dot in the domain part (will not check for a valid TLD though):

function isValidEmail($email) {
    return filter_var($email, FILTER_VALIDATE_EMAIL) 
        && preg_match('/@.+\./', $email);
}

This problem only exists before PHP 5.3, in that version they changed the regex and now it does this check, so you do not have to.