Release 0.6:

Message attachment searchability automatically takes effect on new messages,
but if you want it on older ones, you'll have to reindex them. See the
instructions below, and the help for sup-sync, for how to do this.

Release 0.5:

Saving message state (pressing "$") has been sped up. However, this is only
automatically in effect for new messages. To make it effective for older
messages (i.e. messages indexed with versions of Sup before 0.5), you must
reindex them, e.g. by running sup-sync --all on a source.