Somebody in the thread at some point said:
At 11:25 AM +0100 7/30/07, Andy Green wrote:
...
> - insist on proper Helo FQDN (lot of spam tools and viruses don't
> take care of this)
...
Do you require the name to be real, or only in valid form? That is, do you
do a DNS lookup on the name?
All of the above.... (this is from /etc/postfix/main.cf)
smtpd_helo_required = yes
smtpd_helo_restrictions =
# our personalized list of accepts and denys based on HELO name
check_helo_access hash:/etc/postfix/helo_access,
# talk to our local boxes that want to send through us
permit_mynetworks,
# no Reverse DNS gets the boot
reject_unknown_client,
# reject bad syntax hostname
reject_invalid_hostname,
# non FQDN gets the boot
reject_non_fqdn_hostname
and after that it checks it against the blackhole DNS server and then
greylisting.
-Andy