Many "Incoming...." files in ~/Mail

[Al Arduengo]

I just noticed that there are a bunch of files in the top of My Mail dir
that seem to contain copies of all the individual messages found in the
separate directories under Mail.  Each of them has several mesages
catted together but I can't figure out the method as there are several
from one fetch session and they aren't related by my splitting methods.
An example of file names is

Incoming28628_fs
Incoming28628kOk

What gives?

-Al
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