spam avoidance (was Re: cpu speed problem)

Andy Green andy at warmcat.com
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/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




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