I'm pleased to announce the release of muchsync: http://www.muchsync.org/
Muchsync is a notmuch mail synchronizer. It lets you keep a full copy of your notmuch database on every one of your computers. Muchsync properly synchronizes maildir contents and notmuch tags, obeying the no lost updates rule and sensibly but conservatively resolving update conflicts with no manual intervention. After initialization (which is slow because it has to download and re-index all of your mail), muchsync is bandwidth efficient and works well over high-latency networks. It is much faster than alternatives such as offlineimap, particularly when you have lots of different maildirs. I originally had plans to rename the utility syncmuch and add tons of features. However, as soon as I ran the first tests of the system, I found that I could not go back to any other way of reading email and my test became production use. Just this base functionality has been enough to solve all of my email problems for the last 13 months. I'm therefore releasing it in the hopes that others will similarly find it useful. (And if muchsync ever takes off, there are small changes to the notmuch API we can discuss that would make it even more efficient...) David