Re: [cobalt-security] Pros & Cons of change to Sendmail and can you do this on a Qube 3 ?

[DNSAdmin <dnsadmin@xxxxxxxxxxxxx>]

At 01:45 PM 5/4/2004, you wrote:
> Hi Folks,
>
> Was reading something at lunch and the writer said he "believed" that
> Sendmail already supported what he was proposing - configuring mail servers
> to drop e-mails from servers whose IP does not match the FROM domain.
>
> I guess first, CAN Sendmail be configured to do this and if so is that
> supported on the Qube 3.
>
> And then of course are there any negative ramifications of doing this ?
> Obviously it will reject any sender email not ID'ing the sending email
> server but is there legitimate email that comes that way ?
>
> Thanks !

My RaQ3s and RaQ4s already do this by default. I have done some sendmail.cf 
tweaks, but nothing that would have affected that. I would assume your Cube 
would have been configured the same.

Look though your /var/log/maillog and look for rejections based on 'domain 
of sender.'

May  4 10:58:51 mailer sendmail[4006]: i44EwpC04006: ruleset=check_mail, 
arg1=<gxdrs@xxxxxxxxxx>, relay=[12.109.64.201], reject=501 5.1.8 
<gxdrs@xxxxxxxxxx>... Domain of sender address gxdrs@xxxxxxxxxx does not exist