A few new features, various behavioral tweaks, and numerous bug fixes. Detailed release notes can be seen here. The highlights are:

  • Supports inline images in Markdown mode. Markup for referencing an attached image is inserted when adding an image to the textview (dragging or pasting).
  • Opens links in the composer when hitting the enter key.
  • Now derives a name from other headers if a Reply-To header does not include the name of the recipient.
  • Added “Reply List” menu item (⌥⌘R).
  • Added hidden preference (MmMessagesOutlineMoveStrategy) to control how the message selection changes when moving messages out of the currently selected mailbox.
  • Handles (removes) Re:-prefixes in Chinese and other languages when generating the subject line for a reply.