Re: Sender header?

[Graham Murray <graham@barnowl.demon.co.uk>]

Stainless Steel Rat <ratinox@peorth.gweep.net> writes:

> Yes, that is exactly what I think.  A records are required for all machines
> on the Internet that have anything to do with mail, and MX records should
> exist for all such hosts.  Proper mail handling depends on that being the
> case.  If your host has neither A nor MX records then it is not configured
> correctly.  Trying to make Gnus work around that does not fix the problem.

I think that there are at least 2 situations in which that does not
apply.

1) Dial-up hosts using dynamic IP. In this situation, the user is
   often given a mailbox of user@isp.com. There are MX records for
   isp.com which points at the ISP's mail server(s). However there is
   no (fixed) A record for the customer's system, and its name is
   dynamically assigned when the system connects to the
   ISP. Therefore, it is not possible to configure the system with its
   FQDN.

2) Hosts on an internal LAN (probably using RFC 1918 addresses) behind
   a firewall. All users on the LAN are allocated mailboxes in the
   form of user@x.com. Internally the hosts on the LAN are configured
   as a.x.com, b.x.com etc. The internal host names should never be
   visible to the Internet "at large". Currently if user@a.x.com
   sends mail with a from address of user1@x.com (the externally
   visible mailbox), gnus will set the Sender to user@a.x.com - which
   address should be visible outside of x.com's internal network.