Perttu Luukko <perttu.luukko@iki.fi> writes:


> The vast majority of these ignored mails are not ignored after I
> transfer them with offlineimap to another computer. I can non-ignore
> these files probably by copying the renamed file back to the mail
> server, so this is fixable. Offlineimap shouldn't mess with the file's
> contents, so is there something that can cause notmuch to ignore a file
> based on its name?

The most likely cause is that the files are mboxes, whether intentional
or not.  In particular if they start with a "From " (note the lack of :)
and contain a second "From " at the beginning of a line later in the
file. In this case something like sed can replace the initial 
"From " with "X-Envelope-From: ".

I agree that the error message could be more informative in this case.

d