[CentOS] Sendmail, mailertable and DNS weirdness.

Wed Jun 21 12:00:33 UTC 2006
Will McDonald <wmcdonald at gmail.com>

On 21/06/06, Bart Schaefer <barton.schaefer at gmail.com> wrote:
> On 6/21/06, Will McDonald <wmcdonald at gmail.com> wrote:
> >
> > I thought mailertable entries bypassed DNS?
>
> Are you sure there's not some other DNS-based check involved, such as
> (not that it would be this specific one) the
> sender-domain-must-resolve check for spam prevention?  Just because
> sendmail doesn't use DNS to reach the destination MTA doesn't mean it
> isn't attempting to validate the message via DNS lookups.

I couldn't say for sure but I don't think this is the case. DNS *is*
actually working for everything bar one domain.
'accept_unresolvable_domains' wasn't defined but the hosts all mail
for the non-existent domain originates from would be listed in
/etc/mail/access.

The sendmail.mc is as follows...

define(`confDEF_USER_ID',``8:12'')dnl
define(`confTO_CONNECT', `1m')dnl
define(`confTRY_NULL_MX_LIST',true)dnl
define(`confDONT_PROBE_INTERFACES',true)dnl
define(`PROCMAIL_MAILER_PATH',`/usr/bin/procmail')dnl
define(`ALIAS_FILE', `/etc/aliases')dnl
define(`STATUS_FILE', `/var/log/mail/statistics')dnl
define(`UUCP_MAILER_MAX', `2000000')dnl
define(`confUSERDB_SPEC', `/etc/mail/userdb.db')dnl
define(`confPRIVACY_FLAGS', `authwarnings,novrfy,noexpn,restrictqrun')dnl
define(`confAUTH_OPTIONS', `A')dnl
define(`confTO_IDENT', `0')dnl
FEATURE(`no_default_msa',`dnl')dnl
FEATURE(`smrsh',`/usr/sbin/smrsh')dnl
FEATURE(`mailertable',`hash -o /etc/mail/mailertable.db')dnl
FEATURE(`virtusertable',`hash -o /etc/mail/virtusertable.db')dnl
FEATURE(redirect)dnl
FEATURE(always_add_domain)dnl
FEATURE(use_cw_file)dnl
FEATURE(use_ct_file)dnl
FEATURE(local_procmail,`',`procmail -t -Y -a $h -d $u')dnl
FEATURE(`access_db',`hash -T<TMPF> -o /etc/mail/access.db')dnl
FEATURE(`blacklist_recipients')dnl
EXPOSED_USER(`root')dnl
FEATURE(`greet_pause', `5000')dnl 5 seconds
DAEMON_OPTIONS(`Port=smtp, Name=MTA')dnl
LOCAL_DOMAIN(`mailscanner1')dnl
MAILER(smtp)dnl
MAILER(procmail)dnl

I wonder, the other domain we routed mail for via mailertable is also
included in /etc/mail/relay-domains, the domain we couldn't route for
isn't.

Will.