Embedded images are attached with bad names.

I'm pretty sure that all drupal-7.20-release-notes are important when an image is loaded online from the site, but they're unsignificant when image is attached to some email message as a file.
I can't simulate situation, in which this query strings will be usefull.
Furthermore, if an email client has the feature "save attachement as", without query strings it will be easier to do.

First of all, I found a mistake in my patch - it shouldn't work. But I've just developed a new version.

1. Function attachRegex is used only for embedded images.
2. Token is used for preventing creating styled images at the server automatically by an unauthorized user. In our case all images have already created and they will be attached to email letter. Therefore, token is absolutely useless. Furthermore, it breaks filename (in file system terminology filename is name and extension, extension '.png&q=salf' is ridiculous).
3. There is the another hypothetical mistake - several images with the same name (for example, images /tmp/folder/1.png and /tmp/folder2/1.png will be attached with the same name "1.png"). As I found, there are problems with such attachments in some cases.

New patch solve all problems in above list.

As I read in release notes, images styles tokens was introduced in Drupal 7.20. In previous Drupal versions the $matches argument of the attachRegex function doesn't contain the key #5, but now this argument is passed with this key, which contains the image style token. Due to this key the attachRegex function returns the path with the token, but the addHTMLImage function is called without this token, and the image is not correctly embedded.

  /**
   * A preg_replace_callback used to attach local files, if possible.
   *
   * @see get()
   */
  protected function attachRegex($matches) {
    if ( ($url = drupal_strip_dangerous_protocols(urldecode($matches[4])))
      && ($path = url_to_realpath($url))
      && is_file($path)
      && $this->addHTMLImage($path, NULL, $path)
    ) {
      // The parent method will replace this with the actual cid: string.
      $matches[4] = $path;
    }
    return implode('', array_slice($matches, 1));
  }

So, there is at least two ways for solving the problem. First way was described previously here: #1929678: Mail MIME inline images using image_style's do not work with Drupal 7.20.

  /**
   * A preg_replace_callback used to attach local files, if possible.
   *
   * @see get()
   */
  protected function attachRegex($matches) {
    if ( ($url = drupal_strip_dangerous_protocols(urldecode($matches[4])))
      && ($path = url_to_realpath($url))
      && is_file($path)
      // Add the image and include any query string ($matches[5]) in the 3rd
      // "name" parameter. This enables compatibility with the token DoS fix
      // added in Drupal 7.20.
      && $this->addHTMLImage($path, NULL, $path . $matches[5])
    ) {
      // The parent method will replace this with the actual cid: string.
      $matches[4] = $path;
    }
    return implode('', array_slice($matches, 1));
  }

The other obvios way is to ignore token (i.e. the key #5 in $matches argument) in embedded images. As for me, this way is more accurate, because it keeps correct filenames in attachments. All we need to do is to unset the key #5 in the $matches array.

  /**
   * A preg_replace_callback used to attach local files, if possible.
   *
   * @see get()
   */
  protected function attachRegex($matches) {
    if ( ($url = drupal_strip_dangerous_protocols(urldecode($matches[4])))
      && ($path = url_to_realpath($url))
      && is_file($path)
      && $this->addHTMLImage($path, NULL, $path)
    ) {
      // The parent method will replace this with the actual cid: string.
      $matches[4] = $path;
      // Remove any query string for keeping the correct file name in the 
      // attachment. This enables compatibility with the token DoS fix added in 
      // Drupal 7.20.
      unset($matches[5]);
    }
    return implode('', array_slice($matches, 1));
  }

What about images with the same name - I'll try to take into account your advice (thank you for it!) and probably I'll create new issue, maybe for the pear module, because this error may occurs not only in drupal MailMime module. I checked the behaviour of several email clients - all of them processes this situation successfully (KMail too).