can't send mail to hotmail or yahoogroups addresses

[Don Levey]

fedora-list-bounces at redhat.com wrote:
> Hello.
>
> With FC2 I thought I'd have a go at hosting my own mail for the first
> time. Sendmail, procmail, and Dovecot are all working fine, but
> hotmail and yahoogroups seem to be refusing to accept mail from me.
>
> I use a fat mail client (thunderbird) when I'm at home and a web based
> one (horde imp) when I'm away. Thunderbird sends mail using my ISP's
> smtp server, so from there I can send mail to hotmail and yahoogroups
> just fine. When I'm away using the web based client, it uses sendmail
> directly, and the mail sits in /var/spool/mqueue for five days until
> it bounces. 'mailq' shows:
>
>                 /var/spool/mqueue (1 request)
> -----Q-ID----- --Size-- -----Q-Time-----
> ------------Sender/Recipient-----------i5S8v2K3018352     2893 Mon Jun
> 28 09:57 <my at address.com>
>                  (reply: read error from mx1.hotmail.com.)
>                                          <addressee at hotmail.com>
>                 Total requests: 1
>
> What I want to know is this: what do I have to do to sendmail.mc to
> get sendmail to do as thunderbird is doing and just talk smtp to my
> ISP's smtp server for remote delivery, but carry on doing what its
> doing now for local delivery?
>
> Cheers,
>
> Eliot.

So here's what I'm seeing in what you write:
1) Thunderbird does NOT use your local sendmail, but the ISP.
2) Webmail DOES use your local sendmail.

Many servers will reject mail sent directly from cable modems, DSL
connections, etc, especially if those connections are dynamic IP addresses.
Realistically, much of the virus propagation (and spam traffic, from "owned"
machines) is sent directly from these machines.  It looks like Hotmail and
Yahoo are protecting their clients and networks by dropping such traffic.

That being said, there's most likely a solution - Smart Hosting.  You can
send mail from your sendmail installation to your ISP and not directly to
the recipient, as you suspect.  In my sendmail.mc file, I've got a line like
the one below:

	define(`SMART_HOST',`smtp.example.com')dnl

This then sends all outgoing mail to my ISP's server to handle.  I can
accept incoming mail directly, as I set up my own domain name; you could
receive mail from your ISP account by using something like fetchmail.

 -Don