email.php

<?php
if (!function_exists('email')) {
     /**
     * @param array|string $email
     * @param string $assunto
     * @param string $corpo
     * @param string @replyTo
     * @return boolean
     */
    function email($email = null, $assunto = '(Sem Assunto)', $corpo = null, $replyTo = retorno@exemplo.com")
    {
        $mail = new PHPMailer\PHPMailer\PHPMailer(true);

        try{
            $mail->SMTPDebug        = 0;
            $mail->IsSMTP();
            $mail->Host             = "mail.host.com";
            $mail->SMTPAuth         = true;
            $mail->Username         = "user@exemplo.com";
            $mail->Password         = 'senhasegura123';
            $mail->SMTPSecure       = 'tls';
            $mail->Port             = 587;
            /*$mail->SMTPOptions = array(
                'ssl' => array(
                    'verify_peer' => false,
                    'verify_peer_name' => false,
                    'allow_self_signed' => true
                )
            ); */

            $mail->Priority         = 3;
            $mail->Encoding         = 'base64';
            $mail->addCustomHeader('Content-Transfer-Encoding', 'base64');
            $mail->addCustomHeader('MIME-Version', '1.0');
            $mail->SetFrom("naoresponda@exemplo.com", "Meu Nome");
            $mail->AddReplyTo($replyTo, $replyTo);

            $mail->isHTML(true);
            $mail->CharSet          = 'utf-8';
            $mail->Subject          = stripslashes($assunto);
            $mail->Body             = stripslashes($corpo);
            $mail->AltBody          = strip_tags(stripslashes($corpo));

            if (is_array($email)) {
                foreach($email as $addr)
                {
                    $mail->addAddress($addr);
                }
            }
            else {
                $mail->addAddress($email);
            }
            
            $mail->Send();
            return true;
        }
        catch (PHPMailer\PHPMailer\Exception $e) {
            echo 'Mensagem não enviada. Erro: ', $mail->ErrorInfo;
            return false;
        }
    }

}