Thanks, John Hinton
Having had yet another of these errors, I was able to test deleting the first line in the mail file. Removing that single LF fixed the problem.
Still wondering what I should do as this is obviously something that is now very old and very irritating. It is a bug.
John Hinton
A RedHat bug report is your only option if you stay with 0.99. I bit the bullet and upgraded to 1.0.0 with an rpm from rpmforge. The performance is much better. Almost as much improvement as when I first switched from wuimap.