trying to get default excerpt with $post_excerpt

I’m working with the wp-email plugin and having some problems. I’m trying to change it to send just an excerpt instead of the whole post.

By default, the plugin uses $post_content to fill in the content of the email. I’m trying to substitute in $post_excerpt. It works only if I have an excerpt filled in for the post. It won’t take just the first 120 characters or whatever of the post like I assume it would. Can anybody help me get the excerpt?

This looks like the important parts of the code…

// Assign Variables
$post = $wpdb->get_row("SELECT post_name, post_date, post_title, post_excerpt, post_author FROM wp_posts WHERE ID = '$p' AND post_status = 'publish' AND post_password = ''");
$post_id = (int) $post->ID;
$post_title = htmlspecialchars(stripslashes($post->post_title));
$post_date = mysql2date('j F Y', $post->post_date);
$post_excerpt = wpautop(stripslashes($post->post_excerpt));
$post_alt_content = htmlspecialchars(stripslashes($post->post_excerpt));
$post_author = htmlspecialchars(stripslashes($post->post_author));

// Mail Failed Because Of Empty Fields
if(empty($yourname) || empty($youremail) || empty($friendname) || empty($friendemail) || empty($post)) {
echo '<p>';
echo '<b>Error</b><br />';
echo '<b>&raquo;</b> Some Fields Are Not Filled In<br />';
echo '<b>&raquo;</b> This Is A Private Post<br />';
echo '</p>';
echo '<p><a href="javascript:history.go(-1);">Click Here To Go Back</a></p>';
exit();
}

// Assign Text
$mail_body = "<p>This page was sent to you by $youremail</p><p><strong>Message:</strong><br />$yourremarks</p><p><strong><a href=".get_permalink().">$post_title</a></strong> | $post_date<br />$post_excerpt<br /><br /><a href=".get_permalink().">".get_permalink()."</a></p>

<p>&nbsp</p><p>Article taken from ".get_bloginfo('name')." - ".get_bloginfo('url')."</p><p>URL to article: ".get_permalink()."</p>";