Form

<?php


class dekaForm{


	function getData(){

		$data = "";
		$data[] .= fw_get_db_settings_option('email_form');
		$data[] .= fw_get_db_settings_option('subject');
		return $data;
	}

	function renderDekaForm(){

		$form  = "";
		$form .= "<form id=\"consForm\" name=\"consForm\" method=\"post\">";
		$form .= "<input id=\"email\" name=\"email\" type=\"email\" placeholder=\"Ваш e-mail\">";
		$form .= "<div id=\"subBlock\">";
		$form .= "<input id=\"submitBtn\" name=\"submitBtn\" type=\"submit\" value=\"Отправить\"><i class=\"fa fa-long-arrow-right\" aria-hidden=\"true\"></i>";
		$form .= "</div>";
		$form .= "</form>";
		$form .= "<div id=\"status-area\">";
		$form .= "</div>";

		echo $form;

	}
	function getValuesAndSubmit($input_value){



		$email 		= "Новая заявка на консультацию: " . $input_value ;
		$to    		= $this->getData()[0];
		$subject 	= $this->getData()[1];
		$headers   	= array();

		$headers[] 	= "MIME-Version: 1.0";
		$headers[] 	= "Content-type: text/plain; charset=UTF-8";
		$headers[] 	= "From: <dekaroom>";
		$headers[] 	= "Bcc: <{$input_value}>";
		$headers[] 	= "Reply-To: <{$input_value}>";
		$headers[] 	= "Subject: {$subject}";
		$headers[] 	= "X-Mailer: PHP/".phpversion();

		mail($to, $subject, $email, implode("\r\n", $headers));
	}

}

Вывод формы 

	<?php
		$deka_form = new dekaForm();

		$deka_form->renderDekaForm();

		if(isset($_POST['email']))
		{
			$input_value = $_POST['email'];

			$deka_form->getValuesAndSubmit($input_value);
		}

		?>

AJAX 
<script>
		jQuery(document).ready(function() {

			jQuery("#consForm").submit(function() {
				jQuery.ajax({
					type: "POST",
					data: jQuery(this).serialize()
				}).done(function() {
					jQuery(this).find("input").val("");



						jQuery('#status-area').flash_message({
							text: 'Спасибо, отправлено!',
							how: 'append'
						}).css({
							'text-transform':'uppercase',
							'font-size':'12px',
							'padding-top':'20px'
				});



					jQuery("#consForm").trigger("reset");
				});
				return false;
			});




			(function($) {
				jQuery.fn.flash_message = function(options) {

					options = $.extend({
						text: 'Done',
						time: 1100,
						how: 'before',
						class_name: ''
					}, options);

					return jQuery(this).each(function() {
						if( jQuery(this).parent().find('.flash_message').get(0) )
							return;

						var message = jQuery('<span />', {
							'class': 'flash_message ' + options.class_name,
							text: options.text
						}).hide().fadeIn('fast');

						jQuery(this)[options.how](message);

						message.delay(options.time).fadeOut('normal', function() {
							jQuery(this).remove();
						});

					});
				};
			})(jQuery);




		});
	</script>