Hi,
>> Why doesn't exim support XCLIENT?
>
> Exim's anti-spam architecture doesn't need it.
>
> I'm surprised that you need to do anti-spam things with an Exim running
> behind an anti-spam proxy.
exim is an MTA. A very extensible MTA, but with no real anti-spam
features. It doesn't have built-in greylisting. spamd can be called, but
only one spamd, not several different spamfilters to add results (at
least not without tricky piped and re-injected exim instances). Exim
works fine as an MTA but obviously does not have (as no other MTA has)
distributed checksum algorithms syncronized to high available databases
to categorize an email to "clean", "bulk", "spam" and so on. So a
serious antispam setup requires more than exim and more than a pure
eXpurgate installation.
