Although it's labelled as for mail stuck in the Outbox, it also works
in other folders. If you don't know whether to use the 32-bit version
or the 64-bit version, try the 32-bit version first. Certain common
antivirus programs, such as most of those from Norton or McAfee,
tend to cause this problem now and then, so if you have such a
program, remember where to find the fix, since you are likely to
need it again, although not immediately.