local mail delivery

[mikko]

Hi,

I am wondering how should I setup a server.
I have installed spamassassin, and am using
fetchmail to get mail from another host.
Now, I wouldn't want to install procmail.

I do not understand how the mail travels:

I make a ssh connection to start imapd
on the target mail-host with fetchmail, to
get the mail, but to whom program does
fetchmail give it to? sendmail? Or does it
put it directly in the mailspool?
Some other program?

I have spamd running, so does it know
that sendmail/spool/other is getting these mails,
and would know to scan them?

I am running 5.1 "out-of-the-box" with
programs installed from a recent ports-tree.

Thank you in advance.