Strange error with mairix and a maildir stored by mutt

[Kurt Hackenberg]

On 2021/03/25 16:37, Chris Green wrote:

> Brilliant! :-)  That was it.  I've not seen an error like that before
> but I guess it must be because of when I did something to that message
> relative to when the mairix index was built.

You replied to that message. That's what the R in the filename means. 
See Wikipedia on maildir: <https://en.wikipedia.org/wiki/Maildir>

Apparently you use mairix on a live set of messages. If so, this will be 
an ongoing problem. You might want to rebuild mairix's index 
automatically, perhaps nightly.