SOHO Email Hosting or Alternatives

[Ben Scott]

On 4/23/07, Python <python at venix.com> wrote:
>> Mailbox host rejects spam message during SMTP, alias host tries to
>> send a DSN for spam message, which bounces, resulting in backscatter
>> problems and lots of headaches for alias host postmaster.
>
> I don't really understand this point.  Aren't DSN concerns essentially
> the same between the alias host and the mailbox host?

  A lot of mail servers reject spam during the SMTP transaction.  If
there is no forwarding involved, the spam cannons just bounce off the
mail server.  (Legitimate failures generate a DSN at the originating
system, which also works fine.)  But add in an alias/forwarding
system.  Now the alias host accepts the spam, and tries to forward it
on to the forwarding target.  The target MX rejects during the SMTP
transaction from the forwarder.  Since the forwarder is not the
originator, it has to generate a DSN, and then attempt to deliver said
DSN to the originating system, based on the information from the SMTP
envelope.  Since that information is almost always forged, the alias
host ends up trying to deliver tons of DSNs to all sorts of bogus
addresses -- some of which match to real people, who then email the
postmaster of the alias host and ask them to stop emitting
backscatter.  (Or, more likely, threaten bodily harm and/or legal
action.)

  Did that make sense, or just confuse the issue further?  :)

-- Ben