Changes were made to HandyNotes_Mailboxes v1.07 to make it work with HandyNotes (tempfix) v1.16b or above. Since those changes involved the Astrolabe update it works with the official release of HandyNotes as well as the tempfix I had posted while waiting on that release.
HanyNotes_Mailboxes (tempfix) also works with HandyNotes 1.2.0 (original version) available on Curse and WowInterface.
It automagically adds a mailbox icon to your minimap and world map whenever you visit a mailbox.
This is not intended as a fork in the code just a working copy until the original author reappears.