<?php

$email='1542666686@.qq.com';
$pattern="/([a-z0-9][-_.]?[a-z0-9]+)@([a-z0-9]*[-_]?[a-z0-9]+)+.{2,3}(.{2})?/i";
if(preg_match($pattern,$email)){

echo '邮箱验证通过!';

} else{

echo '邮箱格式错误!';

}
?>