spam avoidance (was Re: cpu speed problem)

Andy Green andy at
Mon Jul 30 22:45:37 UTC 2007

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/

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
  # no Reverse DNS gets the boot
  # reject bad syntax hostname
  # non FQDN gets the boot

and after that it checks it against the blackhole DNS server and then


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