PHP Send Mail (Plaintext and HTML)

send_email.php

<?php
/**
 * Send email
 * @param string|array $email
 * @param object $from
 * @param string $subject
 * @param string $message
 * @param string $headers optional
 */
function send_email($email, $from, $subject, $message, $headers = null)
{
	// Unique boundary
	$boundary = md5( uniqid() . microtime() );

	// If no $headers sent
	if (empty($headers))
	{
		// Add From: header
		$headers = "From: " . $from->name . " <" . $from->email . ">\r\n";

		// Specify MIME version 1.0
		$headers .= "MIME-Version: 1.0\r\n";

		// Tell e-mail client this e-mail contains alternate versions
		$headers .= "Content-Type: multipart/alternative; boundary=\"$boundary\"\r\n\r\n";
	}

	// Plain text version of message
	$body = "--$boundary\r\n" .
	   "Content-Type: text/plain; charset=ISO-8859-1\r\n" .
	   "Content-Transfer-Encoding: base64\r\n\r\n";
	$body .= chunk_split( base64_encode( strip_tags($message) ) );

	// HTML version of message
	$body .= "--$boundary\r\n" .
	   "Content-Type: text/html; charset=ISO-8859-1\r\n" .
	   "Content-Transfer-Encoding: base64\r\n\r\n";
	$body .= chunk_split( base64_encode( $message ) );

	$body .= "--$boundary--";

	// Send Email
	if (is_array($email))
	{
		foreach ($email as $e)
		{
			mail($e, $subject, $body, $headers);
		}
	}
	else
	{
		mail($email, $subject, $body, $headers);
	}
}

usage.txt

A simple function for sending email(s) using PHP's built in mail function. This function will send both html and plain text versions in the email.

Notes:
This first parameter ($email) of this function will accept one email as a string or an array of emails.
The second parameter ($from) is an object with two properties; $from->name and $from->email.

uniqid() is already microtime() based. REF: https://www.php.net/manual/en/function.uniqid.php

It is recommended that you use uniqid('',TRUE) if you want more guarantee of uniqueness.

Today you can use charset=UTF-8 instead of charset=ISO-8859-1.

PHP 8.2 good practices would be to add types for the parameters and a return type. Thanks for the function !