Not only is it possible but I just did it, or at least I was able to go into aptitude, delete exim4, exim4-base, exim4-config, and exim4-daemon-heavy, and add postfix and it's not reporting any conflicts
...and in particular no conflicts with my apache2 installation, which is a stock installation straight from the packages -- about the only weird thing I'm doing is using the multithreaded mpm module, which apparently nobody does these days, but that shouldn't matter for anything external to apache...)
Since I don't have a real Postfix config ready to go and I need to keep a working mail server, I'm not quite up for typing 'g' to see what explodes when I Actually Do it. But at least this shows your webserver package, whatever it is, is just b0rken.
... which I realize may not help you a whole lot, though if this is indeed an apache1 packaging issue, and that's what you're using, an upgrade to apache2 apparently would be one way out of this box.
no subject
...and in particular no conflicts with my apache2 installation, which is a stock installation straight from the packages -- about the only weird thing I'm doing is using the multithreaded mpm module, which apparently nobody does these days, but that shouldn't matter for anything external to apache...)
Since I don't have a real Postfix config ready to go and I need to keep a working mail server, I'm not quite up for typing 'g' to see what explodes when I Actually Do it. But at least this shows your webserver package, whatever it is, is just b0rken.
... which I realize may not help you a whole lot, though if this is indeed an apache1 packaging issue, and that's what you're using, an upgrade to apache2 apparently would be one way out of this box.