I write links to notmuch threads into my todo list in org-mode.

I then try to visit these threads on a different machine, but of course
that thread id doesn't exist there, since the database was reindexed and
tags reimported.

I don't know if it is in any way practical, but it would be nice from my
point of view if thread id's were a property of the mail collection, or
at least it was possible to dump and restore them.

If this is too much of a corner case, then I suspect I can work around
it in the emacs client by calling search twice, first with an id in the
thread.

David