Simon Josefsson <jas@extundo.com> writes:
SJ> Could you evaluate (nnml-marks-changed-p "nnml+foo:bar") to see if it
SJ> always return t?

Yes, it does.  My theory is that this happens because
nnml-marks-changed-p tests whether the value gnus-gethash returns is
eq to the modtime returned by file-attributes; since they're
presumably not going to be the same object (I'd expect file-attributes
to return a new list every time), you want to test equality with
equal, rather than eq.