[artcraft]

вот, то что надо:

String.prototype.isEmail = function(){
	//email address has to have at least 5 chars
	if (this.length < 5){return false;}

	var iChars = "*|,\":<>[]{}`';()&$#%";
	var eLength = this.length;
	for (var i=0; i < eLength; i++)	{
		if (iChars.indexOf(this.charAt(i)) != -1){
			trace("Invalid Email Address : Illegal Character in Email Address : -->" + this.charAt(i) + "<--.");
			return false;
		}
	}

	var atIndex = this.lastIndexOf("@");
	if(atIndex < 1 || (atIndex == eLength - 1)){
		trace("Invalid Email Address : Email Address must contain @ as at least the second chararcter.");
		return false;
	}

	var pIndex = this.lastIndexOf(".");
	if(pIndex < 4 || (pIndex == eLength - 1)){
		trace("Invalid Email Address : Email Address must contain at least one . (period) in a valid position");
		return false;
	}

	if(atIndex > pIndex){
		this.__error = "Invalid Email Address : Email Address must be in the form of name@domain.domaintype";
		return false;
	}

	return true;
}