[CentOS] sendmail mail relay backscatter issue.

Simon Billis simon at houxou.com
Fri Feb 5 11:06:36 UTC 2010


> On 2/4/2010 3:31 PM, Kai Schaetzl wrote:
> >> What do you mean?  Forwarding to the virtuser expansion address
> should
> >> work just like any other address.
> >
> > It sounds like he didn't forward before, but queue and deliver (e.g.
> he's
> > the only available MX and queues for a firewalled MX or uses
> mailertable
> > to get the mail delivered). If he goes to virtusertable he has to
> fill the
> > table with valid forwards.
> The point would be able to include a default reject rule for each
> domain, which means that you have to supply valid forwards for all
> addresses you don't want to reject at the relay.  (You could default to
> forwarding, but that doesn't help with the backscatter issue).  But
> that
> doesn't change the ability to queue/deliver except that the relay has
> to
> accept the domains as local to do the virtuser lookup so the new target
> has to have a different name for the delivery host.   I'm not sure how
> that relates to your distinction between forwarding and queuing.
> Sendmail has local and remote addresses, but remote ones all go through
> the same steps.

I am queuing and delivering using mailertable currently - hence the issue
with backscatter as some of the domains do not have catch-all accounts. I am
able to produce a list of valid email accounts and domains without a
catch-all account so I should be able to create a virtusertable with the
required entries to either accept all mail for a domain and then forward it
to a specific account (the catch-all account) or to only accept mail for a
specific account and then forward it to the same address (is this valid?) by
again using mailertable(?). I think that using access.db and relay-domains
may also work as needed.

Thanks very much for your help with this and the suggestions it is much


More information about the CentOS mailing list