> But sorting a summary buffer of 5K messages on Date (which some people
> do) might get a performance boost.  But I was thinking that it might be
> more likely that parse-datetime parses more date strings correctly than
> the version in parse-time.el.  

It looks that way, i.e. parse-time-string is pretty simple compared to
that.  But most Date header I've seen popping up in my mail seem to
adhere to a strict rfc2822 format anyway, except for the occasional
non-strict timezone.

-ap