Thunderbird search fails to find messages (3.1.9) solved

[ChrisGreaves]

Yes, I see that Thunderbird 5 is released. I'm going to upgrade Real Soon Now^(TM).

In the meantime, I was puzzled that I couldn't find the email I *know* I sent off last Thursday.
This (forums.mozillazine.org) Post gave me a clue.

I deleted all the *.MSF and found the lost message.

P.S. (later) I realize now that I must have done this before. One of the side-effects is that several messages in odd folders are suddenly marked as "not read".