Smtpd spam prevention

[sirjofri <sirjofri+ml-9front@sirjofri.de>]

Hello all,

my smtpd server runs fine, but I recently got some spam mails. Currently 
my server doesn't filter anything and does nothing to prevent spam.

There are two options to smtpd, according to the man:

> -D sleeps for 15 seconds usually at the start of the SMTP
> dialogue; this deters some spammers.  Connections from
> Class A networks frequented by spammers will incur a
> longer delay.

> -g turns on grey/white list processing.  All mail is
> rejected (with a retry code) unless the sender's IP
> address is on the whitelist, /mail/grey/whitelist, an
> append only file.  Addresses can be added to the whitel-
> ist by the administrator.  However, the usual way for
> addresses to be added is by smtpd itself. ... (Greylisting)

Both options make sense to me. -g might work out of the box, is there 
anything I need to know before enabling it?

-D is new to me. I never heard about this extra delay when handling mail. 
Can I safely enable that?

What configurations do you use?

I don't want to dive into ratfs for now. My mail traffic is low anyways.

sirjofri