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

[derek at ihtfp.com (Derek Atkins)]

Hi Rich,

On Tue, March 29, 2016 1:15 pm, Rich Pieri wrote:
> Postfix out of the box should not permit what you describe so I think
> you broke something. Things to check in main.cf: mydestination,
> mynetworks, relay_domains, and smtpd_relay_restrictions.

I thought so, too.  Here's what I've got:

mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain,
/etc/postfix/hostlist

mynetworks = 127.0.0.0/8 <my class C>/24 192.168.X.0/24
[2001:xxxx:yyyy::]/48 [::1]/128 [fe80::]/10

relay_domains is not set

smtpd_relay_restrictions =

For kicks I just added reject_unauthenticated_sender_login_mismatch to my
smtpd_sender_restrictions:

smtpd_sender_restrictions = permit_mynetworks,
	permit_tls_clientcerts,
	permit_sasl_authenticated,
	check_sender_access hash:/etc/postfix/goodsender,
	check_sender_access hash:/etc/postfix/badsender,
	reject_unknown_sender_domain,
	reject_non_fqdn_sender,
	check_sender_access hash:/etc/postfix/sender_access,
	reject_unverified_sender,
	reject_unauthenticated_sender_login_mismatch,
	permit

> Not sure off-hand what the sendmail equivalents are.

This is my bigger concern....  :(

One of these years I should just migrate that server over to postfix.

> Rich P.

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