Form to include dynamically into your post with shortcode.

contact-form-shortcode.php

<?php

function drawContactForm($contactFor = 'personal'){
	ob_start();
	$randomName = generateRandomString();
?>
	<form name="form-<?php echo $randomName; ?>" action="" method="post">
			
			<div id="comment-input">
				<div class="row">
					<label><?php echo __('First Name', 'Avada'); ?> <span>*</span>
						<input type="text" name="first_name" id="author" value="<?php if(isset($_POST['first_name']) && !empty($_POST['first_name'])) { echo $_POST['first_name']; } ?>" size="22" tabindex="1" aria-required="true" class="input-name">
					</label>
					<label><?php echo __('Last Name', 'Avada'); ?> <span>*</span>
						<input type="text" name="last_name" id="last_name" value="<?php if(isset($_POST['last_name']) && !empty($_POST['last_name'])) { echo $_POST['last_name']; } ?>" size="22" tabindex="2" aria-required="true" class="input-name">
					</label>
				</div>
				<div class="row">
					<label><?php echo __('Email', 'Avada'); ?> <span>*</span>
						<input type="text" name="email" id="email" value="<?php if(isset($_POST['email']) && !empty($_POST['email'])) { echo $_POST['email']; } ?>" size="22" tabindex="2" aria-required="true" class="input-name">
					</label>
					<label><?php echo __('Company', 'Avada'); ?> <span>*</span>
						<input type="text" name="company" id="company" value="<?php if(isset($_POST['company']) && !empty($_POST['company'])) { echo $_POST['company']; } ?>" size="22" tabindex="3" class="input-name">
					</label>
				</div>
				<div class="row">
					<label><?php echo __('Phone Number', 'Avada'); ?> <span>*</span>
						<input type="tel" name="phone_number" id="phone_number" value="<?php if(isset($_POST['phone_number"']) && !empty($_POST['phone_number"'])) { echo $_POST['phone_number"']; } ?>" size="22" tabindex="3" class="input-name">
					</label>
					<label><?php echo __('Alternate Phone Number', 'Avada'); ?>
					<input type="tel" name="phone_alternate" id="phone_alternate" value="<?php if(isset($_POST['phone_alternate']) && !empty($_POST['phone_alternate'])) { echo $_POST['phone_alternate']; } ?>" size="22" tabindex="3" class="input-name">
				</div>
				
			</div>
			
			<div id="comment-textarea">
				<div class="row">
					<label><?php echo __('Message', 'Avada'); ?> <span>*</span></label>
					<textarea name="msg" id="comment" cols="39" rows="4" tabindex="4" class="textarea-comment"><?php if(isset($_POST['msg']) && !empty($_POST['msg'])) { echo $_POST['msg']; } ?></textarea>			
				</div>
			</div>

			
			<div id="comment-submit">
				<p><div><input name="submit" type="submit" id="submit" tabindex="5" value="<?php echo __('Submit', 'Avada'); ?>" class="comment-submit button small green"></div></p>			
			</div>
			<input type="hidden" name="contactTo" value="<?php echo $contactFor; ?>">
	</form>

<?php
	$output = ob_get_contents();
	ob_end_clean();

	return $output;
}

function generateRandomString($length = 10) {
    $characters = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, strlen($characters) - 1)];
    }
    return $randomString;
}

// Add Shortcode
function basic_contact_form_shortcode( $atts ) {

	// Attributes
	extract( shortcode_atts(
		array(
			'email_address_to' => '',	
			'subject_prefix'=> '',
		), $atts )
	);

	//If the form is submitted
	if(isset($_POST['submit']) && $subject_prefix == trim($_POST['contactTo'])) {
		//Check to make sure that the name field is not empty
		if(trim($_POST['first_name']) == '') {
			$hasError = true;
		} else {
			$first_name = trim($_POST['first_name']);
		}

		if(trim($_POST['last_name']) == '') {
			$hasError = true;
		} else {
			$last_name = trim($_POST['last_name']);
		}

		//Subject field is not required
		$subject = 'Contact from [' . $subject_prefix . ']';

		//Check to make sure sure that a valid email address is submitted
		if( trim($_POST['email']) == '')  {
			$hasError = true;
		} else if (!eregi("^[A-Z0-9._%-]+@[A-Z0-9._%-]+\.[A-Z]{2,4}$", trim($_POST['email']))) {
			$hasError = true;
		} else {
			$email = trim($_POST['email']);
		}

		if(trim($_POST['company']) == '') {
			$hasError = true;
		} else {
			$company = trim($_POST['company']);
		}

		if(trim($_POST['phone_number']) == '') {
			$hasError = true;
		} else {
			$phone_number = trim($_POST['phone_number']);
		}

		if(trim($_POST['phone_alternate']) == '') {
			$hasError = true;
		} else {
			$phone_alternate = trim($_POST['phone_alternate']);
		}

		//Check to make sure comments were entered
		if(trim($_POST['msg']) == '') {
			$hasError = true;
		} else {
			if(function_exists('stripslashes')) {
				$comments = stripslashes(trim($_POST['msg']));
			} else {
				$comments = trim($_POST['msg']);
			}
		}

		//If there is no error, send the email
		if(!isset($hasError)) {
			$emailTo = $email_address_to; //Put your own email address here
			$body = __('First Name:', 'Avada')." $first_name \n\n";
			$body .= __('Last Name:', 'Avada')." $last_name \n\n";
			$body .= __('Email:', 'Avada')." $email \n\n";
			$body .= __('Company:', 'Avada')." $company \n\n";
			$body .= __('Phone Number:', 'Avada')." $phone_number \n\n";
			$body .= __('Alternate Phone Number:', 'Avada')." $phone_alternate \n\n";
			
			$body .= __('Message:', 'Avada')."\n $comments";
			$headers .= 'Reply-To: ' . $first_name .' ' . $last_name  . ' <' . $email . '>' . "\r\n";

			$mail = wp_mail($emailTo, $subject, $body, $headers);
			
			$emailSent = true;
		}
	}

	if(isset($hasError)) { //If errors are found 
		echo '<div class="alert error"><div class="msg">'; 
		echo __("Please check if you've filled all the fields with valid information. Thank you.", 'Avada'); 
		echo '</div></div><br />';
	}	

	if(isset($emailSent) && $emailSent == true) { //If email is sent 
		echo '<div class="alert success"><div class="msg"> ';
		echo __('Thank you', 'Avada');
		echo ' <strong>'.$first_name.'</strong> ';
		echo __(' for using our contact form ('.$subject_prefix.')! Your email was successfully sent!', 'Avada');
		echo '</div></div><br />';
	}

	// Code
	return drawContactForm($subject_prefix);

}

add_shortcode( 'basic_contact_form', 'basic_contact_form_shortcode' );

/**
 * 
 * How to use:
 * 1.- include contact-form-shortcode.php into your function theme file.
 * 2.- Create new page or post and include:
 * 
 * [basic_contact_form email_address_to="[email protected]" subject_prefix="Goes into subject email"]
 * 
 * 3.- that's it.
 * 
 * 
*/