I'm trying to use regex to check the validity of an email address in a php script. I use the following string as my regex

```
$reg = "\/^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})\$\/";

```

I keep getting an error:

```
 Warning: preg_match(): Delimiter must not be alphanumeric or backslash

```

I've done my best to escape all special characters. is there something I'm missing?