strange sendmail behavir

[Tim]

On Sun, 2014-05-18 at 12:38 -0500, Steven Stern wrote:
> I have root aliased to "webmaster at mydomain.com" in /etc/aliases.  When
> I use "sendmail -bv root", it shows that the mail will be send to
> "webmaster at mydomain.com".
>  
> But when I use "mail root", the mail goes to
> "root at mylocalhost.mydomain.com".
>  
> Mail is handled by a SMARTHOST statement going out to a gmail mx
> server, but the problem remains if I let it default to finding an MX
> on its own.

I haven't run sendmail on a recent release, but these sorts of things
have caused me grief in the past:

If you want to post to an external mailserver, your "from" address has
to be a real address (the domain name has to have a public IP, at the
very least, that the external service can look up).  They won't accept
mail coming from something at localhost.localdomain, or any fictitious
domain names.

Your machine's hostname has to resolve properly.  If your machine thinks
that it is localhost.localdomain, rather than some-made-up.example.com,
sending mail behaves oddly.

If you've done dopey things with your /etc/hosts files, such as putting
your machine hostname into the localhost lines, instead of into the
lines that are associated with your ethernet port addresses, sending
mail can be screwy.  For what it's worth, I have a properly functioning
DNS server on my LAN, and no machine names in any /etc/hosts files, just
the localhost lines.

Mailservers, and other servers, can do some strange shenanigans to
determine their hostnames, which can trip you up, such as:  Look up the
hostname, find out its numerical IP, reverse look-up that IP, to find
out its hostname.  Or, reverse-lookup its IP to find the hostname, look
up the IP for that hostname, then rinse, lather, repeat.  Either as a
way to find out these things, or as part of the confirmation that the
addresses are correct (e.g. anti-spam techniques).

If something resolves to 127.0.0.1 or localhost, in the middle of such
sequences, everything goes off course from what you expected.

-- 
tim at localhost ~]$ uname -rsvp

Linux 3.14.3-200.fc20.i686 #1 SMP Tue May 6 19:23:18 UTC 2014 i686

All mail to my mailbox is automatically deleted, there is no point trying
to privately email me, I will only read messages posted to the public lists.

George Orwell's '1984' was supposed to be a warning against tyranny, not
a set of instructions for supposedly democratic governments.