[Exim] dialup, PPP, dynamic IP and name, primary_hostname

Hello,

I tried to make exim work on a computer with modem.
Every time I connect, the IP and name of the computer
changes. It means I must change the
primary_hostname
option in /etc/exim.conf and restart exim. After that
it works. Some people wrote a script that modifies
exim.conf but I suppose that it should be possible
that exim asks pppd for the current hostname a uses it.
Or to change the primary_hostname as a command line
option.

If the primary_hostname does not correspond with the
real hostname, it is not possible to send mail
to another computer that performs reverse dns lookup.

If primary_hostname is not set at all, the uname()
function is used instead. Direct change of hostname
via the "hostname" command works with exim, but many
other services crash.


Maybe this problem is already solved and I should
read the manual. Is there any easy solution?

Thanks a lot,
Honza

honza@???