For more context, as I google around more I see people offering
advice/answers similar to the procedure found he
http://www.howto-outlook.com/faq/mes...ckinoutbox.htm

Can anyone offer a technical explanation for this? The more detailed the
better -- probably discussing it in terms of electrons is too detailed.

Unsettled wrote:
I've run into this problem before, and it always seems to be some
magical thing like: move it out of the Outbox, close outlook, restart,
Send and receive, resend, and sometimes it works.

What exactly is the problem? I've suspected it has partly to do with
some sort of locking and how the PST works. As I understand, it's a
database for mail, calendar, and task data.

Is it some glitch in how the PST is? There are many in unix/linux
circles that will barf at the idea of storing mail in a database. Does
it all basically boil down to the mail store?