sendmail questions about deferred messages

[Paul Howarth]

Les Mikesell wrote:
> On Mon, 2006-06-05 at 07:09, Ambrogio wrote:
> 
>>> Sendmail needs to do DNS lookups to canonicalize the address before it 
>>> can determine whether the address is local or not.
>> the hosts file is not enough?
>> I see query to redhat.com for MX when messages is from fedora list.
>> But I think that query should be for my account and so for my MX.
> 
> Sendmail checks the sender's address too. There's an option
> to reject messages that have addresses that DNS can't resolve
> and if you permit them it will add a 'may be forged' comment
> in the headers. 

I think the "may be forged" comment applies when a reverse DNS lookup 
yields a hostname that doesn't resolve back to the same IP address. 
Clearly that would apply for an unresolvable domain, but there are other 
causes as well.

Paul.