I have a followup on this report. Olly suggested quoting the quoting of the id, so that the quoting gets properly passed to Xapian, and that seems to work: 0 servo:~ $ notmuch search id:'"4bd73e8cb3d79_1a3c..fb637ff610e@skinner.tmail"' thread:000000000000c4cf Yest. 15:44 [1/1] XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 0 servo:~ $ So I think this means that the problem probably lies mostly in the emacs UI not properly quoting the id string. What originally got me on this problem is that I was not able to manipulate the tag of this email from within emacs. On Wed, 28 Apr 2010 08:39:57 -0400, Jameson Rollins wrote: > 0 servo$ notmuch search id:4bd73e8cb3d79_1a3c..fb637ff610e@skinner.tmail > A Xapian exception occurred performing query: Unknown range operation > Query string was: id:4bd73e8cb3d79_1a3c..fb637ff610e@skinner.tmail > 0 servo$ I also note here that notmuch is not returning an error, even though a Xapian exception occurred and the search failed. This is another important issue. I'm not sure if I should bring it up in a separate message or not. This goes back to the bug tracking issue. jamie.