my contact us form does not send email

This is my javascript code:

function eMailControl(value)
        {
            var pattern = "^"+"([abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0-9_\.\-]+)"+"@"+"([abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0-9_\.\-]+)"+"[\.]"+"([abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0-9_\.\-]+)"+"$";
            r = new RegExp(pattern, "g");
            return r.test(value);
        }
    function mailFormControl(f){
        $(".alert-contact").hide();
        var alertmessage = "Please fill in all fields";
        if(f.name.value == f.name.defaultValue){
            $(".alert-contact").html("<div class='alert_box info'>Please write your name!<div class='close'></div></div>");
        }else if(!eMailControl(f.email.value)){
            $(".alert-contact").html("<div class='alert_box info'>Please write your email!<div class='close'></div></div>");
        }else if(f.phone.value == f.phone.defaultValue){
            $(".alert-contact").html("<div class='alert_box info'>Please write a Phone!<div class='close'></div></div>");
        }else if(f.message.value == f.message.defaultValue){
            $(".alert-contact").html("<div class='alert_box info'>Please write your message!<div class='close'></div></div>");
        }else{
            $(".alert-contact").html("<div class='alert_box info'>Your message sending...<div class='close'></div></div>");
            $.post("contactus_action.php",  {   name:f.name.value, 
                                        mail:f.email.value,
                                        phone:f.phone.value,
                                        message:f.message.value
                                    },
           function(data) {
            if(data==1){
                $(".alert-contact").html("<div class='alert_box success'>Thank you for your message!<div class='close'></div></div>");
                f.name.value = f.name.defaultValue;
                f.email.value = f.email.defaultValue;
                f.phone.value = f.phone.defaultValue;
                f.message.value = f.message.defaultValue;
            }else{
                $(".alert-contact").html("<div class='alert_box error'>Please try again!<div class='close'></div></div>");
            }
           });
        }
        $(".alert-contact").fadeIn();
    }
    $(".send-message").click(function() {
        mailFormControl(document.messageform);
    });