genuine bulk email

Matthew Seaman m.seaman at
Fri Oct 12 09:39:12 PDT 2007

Hash: SHA256

Robin Becker wrote:

> these all sound very reasonable. However, we use the same IP for several
> virtual hosts ie we have more than one domain name so the reverse DNS is
> not clear to me. Is the from address inspected for comparison with the
> RDNS ie if I claim to be sending from should my RDNS point back
> to Presumably I can have only one IP-->domain ptr. I suspect it
> will be easier to set up the front end machine as that is supposed to be
> for the same client.

Supporting several e-mail domains on one server is not a problem.
There is no general requirement that the mail server for a domain
'' have an address within --- you can quite freely
have your e-mail handled by a third party.

The important things to make sure of are:

   * Your mail server HELOs with a valid domain name, and that
     domain name should correspond to the IP that the mail server
     connects as, both forwards and backwards.  Note: 'connects as'
     -- if your mail server is behind a NAT gateway, you will have
     to take that into account in your configuration.

   * Don't use the sort of domain name that is a thinly disguised
     IP number: eg: -- this sort of
     hostname is a pretty good diagnostic for a spam source and
     some mail admins will go as far as immediately rejecting
     messages from such addresses.

   * Don't use addresses from dynamic IP number pools used for
     residential ADSL services.  These overlaps a great deal with
     the above, and are frequently rejected for much the same sort
     of reasons. (There are entire RBL lists dedicated to enumerating
     such residential IP address blocks).

   * Do use static IP numbers from ranges specifically allocated to

   * Do make sure that you provide appropriate SPF records with
     include the name / IP your mail server HELOs as. Or if you
     aren't a believer in SPF, then either use a neutral entry like
     "v:spf1 ~all" or no entry at all.

   * Make sure that abuse at you.dom.ain, postmaster at you.dom.ain
     and possibly a few other common addresses are accepted by your
     domain, the messages are read and acted upon promptly.  You should
     exempt these addresses as far as possible from all forms of
     anti-spam filtering.



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Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
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