[Discuss] Strange sendmail (and postfix) spam issue: accepting fail "from" myself?

[derek at ihtfp.com (Derek Atkins)]

Rich,

On Tue, March 29, 2016 1:42 pm, Rich Pieri wrote:
> On 3/29/2016 1:24 PM, Derek Atkins wrote:
>> smtpd_relay_restrictions =
>
> This looks like the problem. Remove it entirely from your main.cf and
> restart Postfix. This should bring the default rules which will block
> relay attempts from anyone that does not match $mydestination or is not
> an authenticated user.

I don't think so.  From
http://www.postfix.org/postconf.5.html#smtpd_relay_restrictions :

 For backwards compatibility, sites that migrate from Postfix versions
before 2.10 can set smtpd_relay_restrictions to the empty value, and use
smtpd_recipient_restrictions exactly as before.

So the empty relay_restrictions should imply the equivalence to the
recipient_restrictions.

I think the issue was the lack of sender_login_mismatch issue in the
sender restrictions.

So now I want to focus on Sendmail.  Any sendmail guru's out there?

Thanks,

> Rich P.

-derek

-- 
       Derek Atkins                 617-623-3745
       derek at ihtfp.com             www.ihtfp.com
       Computer and Internet Security Consultant