(Possibly corrupted buffer ' *nnmail incoming*'.)

[Bjørn Harbo]

I have tried to convert from mutt to gnus (5.10) and have renamed my old
Mail-directory to avoid confusion.
My very basic ~/.gnus:
(setq gnus-select-method '(nntp "news.online.no"))
(setq user-mail-address bharbo@online.no)
(setq user-full-name "Bjorn Harbo")
(setq gnus-secondary-select-methods
    '((nnml "private")))
According to http://zez.org/article/articleprint/38/ I then
echo "testmail" | mail -s "testmail" myname
When trying to fire up gnus the following message shows up:

Error, unknown mail format! (Possibly corrupted buffer ' *nnmail
incoming*'.)

Anybody got an idea?