I have a strange problem I don't know how to resolve.

I have server in an internal network without internet access and with internal DNS for local network only. Only some servers have internet access and they use a DNS that can resolve also internet domains.

One server with internet access is used to relay mails out of this network, and servers without internet access use that server as a relay. I configure SMART_HOST and nocanonify on servers without internet access, and until now this was usually enough.

On the latest (Oracle Linux 8 with sendmail 8.15.2), mails that I send to internet addresses are not sent to the relay server. maillog reports that relay is "root@localhost", in this case. I also have an alias for root in /etc/aliases, which is an valid e-mail on internet. If I send an e-mail to root, sendmail uses the configured smart host, and mail gets out. Sending to the same address directly does not work.

I do not need any other mails (than for root) from this server, but I am curious, why is this happening.

Regards
Marko

Marko Hrastovec wrote:

> configured smart host, and mail gets out. Sending to the same address directly does
> not work.

Without any real data it's hard to say what's wrong...

Post the command you use and the logfile entries which it generates.
Also include your mc file.

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> Post the command you use and the logfile entries which it generates.
> Also include your mc file.

Here are the details you were asking for.

I use the following:

1.
- command:
mail -s test name@internet.domain.com
- maillog:
Sep 2 17:50:34 hostname sendmail[770878]: 182HoYH3770878: from=username, size=15, class=0, nrcpts=1, msgid=<202109021750.182HoYH3770878@hostname.internal.domain>, relay=root@localhost
Sep 2 17:50:34 hostname sendmail[770878]: 182HoYH3770878: to=name@internet.domain.com, delay=00:00:00, mailer=relay, pri=30015, dsn=4.4.3, stat=queued

2.
- command:
mail -s testemail root
- maillog:
Sep 2 17:51:08 hostname sendmail[770898]: 182Hp8Wg770898: from=username, size=208, class=0, nrcpts=1, msgid=<202109021751.182Hp8Wg770898@hostname.internal.domain>, relay=root@localhost
Sep 2 17:51:08 hostname sendmail[770898]: STARTTLS=client, relay=[127.0.0.1], version=TLSv1.3, verify=FAIL, cipher=TLS_AES_256_GCM_SHA384, bits=256/256
Sep 2 17:51:08 hostname sendmail[770899]: STARTTLS=server, relay=localhost [127.0.0.1], version=TLSv1.3, verify=NOT, cipher=TLS_AES_256_GCM_SHA384, bits=256/256
Sep 2 17:51:09 hostname sendmail[770899]: 182Hp8mt770899: from=<username@hostname.internal.domain>, size=494, class=0, nrcpts=1, msgid=<202109021751.182Hp8Wg770898@hostname.internal.domain>, proto=ESMTPS, daemon=MTA, relay=localhost [127.0.0.1]
Sep 2 17:51:09 hostname sendmail[770898]: 182Hp8Wg770898: to=root, ctladdr=username (1000/1000), delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=30208, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (182Hp8mt770899 Message accepted for delivery)
Sep 2 17:51:09 hostname sendmail[770900]: STARTTLS=client, relay=relay..public.dmz., version=TLSv1.3, verify=FAIL, cipher=TLS_AES_256_GCM_SHA384, bits=256/256
Sep 2 17:51:09 hostname sendmail[770900]: 182Hp8mt770899: to=name@internet.domain.com, ctladdr=<username@hostname.internal.domain> (1000/1000), delay=00:00:01, xdelay=00:00:00, mailer=relay, pri=30799, relay=relay.public.dmz. [10.163.1.1], dsn=2.0.0, stat=Sent (182Hp9RF550703 Message accepted for delivery)

3.
- command
(echo subject: test; echo) | /usr/lib/sendmail -Am -v name@internet.domain.com
- output
internet.domain.com: Name server timeout
name@internet.domain.com... Transient parse error -- message queued for future delivery
name@internet.domain.com... queued
- maillog
Sep 2 17:50:58 hostname sendmail[770893]: 182HowSp770893: from=username, size=239, class=0, nrcpts=1, msgid=<202109021750.182HowSp770893@hostname.internal.domain>, relay=root@localhost
Sep 2 17:50:58 hostname sendmail[770893]: 182HowSp770893: to=name@internet.domain.com, delay=00:00:00, mailer=esmtp, pri=30239, dsn=4.4.3, stat=queued

4.
- command
(echo subject: test; echo) | /usr/lib/sendmail -Am -v root
- output
internet.domain.com: Name server timeout
name@internet.domain.com... Transient parse error -- message queued for future delivery
name@internet.domain.com... queued
- maillog
Sep 2 18:02:59 hostname sendmail[771149]: 182I2x5i771149: from=username, size=15, class=0, nrcpts=1, msgid=<202109021802.182I2x5i771149@host.internal.domain>, relay=root@localhost
Sep 2 18:02:59 hostname sendmail[771149]: 182I2x5i771149: to=name@internet.domain.com, delay=00:00:00, mailer=relay, pri=30015, dsn=4.4.3, stat=queued

The command 1 does not send the e-mail and nothing stays in queue. The command 2 sends out the e-mail which arrives to my account. Commands 3 and 4 do not get the e-mails out, but they enter the queue.

/etc/sendmail.mc file:
divert(-1)dnl
dnl #
dnl # This is the sendmail macro config file for m4. If you make changes to
dnl # /etc/mail/sendmail.mc, you will need to regenerate the
dnl # /etc/mail/sendmail.cf file by confirming that the sendmail-cf package is
dnl # installed and then performing a
dnl #
dnl # /etc/mail/make
dnl #
include(`/usr/share/sendmail-cf/m4/cf.m4')dnl
VERSIONID(`setup for linux')dnl
OSTYPE(`linux')dnl
dnl #
dnl # Do not advertize sendmail version.
dnl #
dnl define(`confSMTP_LOGIN_MSG', `$j Sendmail; $b')dnl
dnl #
dnl # default logging level is 9, you might want to set it higher to
dnl # debug the configuration
dnl #
dnl define(`confLOG_LEVEL', `9')dnl
dnl #
dnl # Uncomment and edit the following line if your outgoing mail needs to
dnl # be sent out through an external mail server:
dnl #
define(`SMART_HOST', `[relay.public.dmz]')dnl
dnl #
define(`confDEF_USER_ID', ``8:12'')dnl
dnl define(`confAUTO_REBUILD')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
dnl #
dnl # The following allows relaying if the user authenticates, and disallows
dnl # plaintext authentication (PLAIN/LOGIN) on non-TLS links
dnl #
dnl define(`confAUTH_OPTIONS', `A p')dnl
dnl #
dnl # which realm to use in SASL database (sasldb2)
dnl #
define(`confAUTH_REALM', `mail')dnl
dnl #
dnl # PLAIN is the preferred plaintext authentication method and used by
dnl # Mozilla Mail and Evolution, though Outlook Express and other MUAs do
dnl # use LOGIN. Other mechanisms should be used if the connection is not
dnl # guaranteed secure.
dnl # Please remember that saslauthd needs to be running for AUTH.
dnl #
dnl TRUST_AUTH_MECH(`EXTERNAL DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
dnl define(`confAUTH_MECHANISMS', `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN')dnl
dnl #
dnl # Basic sendmail TLS configuration with self-signed certificate for
dnl # inbound SMTP (and also opportunistic TLS for outbound SMTP).
dnl #
define(`confCACERT_PATH', `/etc/pki/tls/certs')dnl
define(`confCACERT', `/etc/pki/tls/certs/ca-bundle.crt')dnl
define(`confSERVER_CERT', `/etc/pki/tls/certs/sendmail.pem')dnl
define(`confSERVER_KEY', `/etc/pki/tls/private/sendmail.key')dnl
define(`confTLS_SRV_OPTIONS', `V')dnl
dnl #
dnl # This allows sendmail to use a keyfile that is shared with OpenLDAP's
dnl # slapd, which requires the file to be readble by group ldap
dnl #
dnl define(`confDONT_BLAME_SENDMAIL', `groupreadablekeyfile')dnl
dnl #
dnl define(`confTO_QUEUEWARN', `4h')dnl
dnl define(`confTO_QUEUERETURN', `5d')dnl
dnl define(`confQUEUE_LA', `12')dnl
dnl define(`confREFUSE_LA', `18')dnl
define(`confTO_IDENT', `0')dnl
dnl # If you're operating in a DSCP/RFC-4594 environment with QoS
dnl define(`confINET_QOS', `AF11')dnl
dnl FEATURE(delay_checks)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
dnl #
dnl # The following limits the number of processes sendmail can fork to accept
dnl # incoming messages or process its message queues to 20.) sendmail refuses
dnl # to accept connections once it has reached its quota of child processes.
dnl #
dnl define(`confMAX_DAEMON_CHILDREN', `20')dnl
dnl #
dnl # Limits the number of new connections per second. This caps the overhead
dnl # incurred due to forking new sendmail processes. May be useful against
dnl # DoS attacks or barrages of spam. (As mentioned below, a per-IP address
dnl # limit would be useful but is not available as an option at this writing.)
dnl #
dnl define(`confCONNECTION_RATE_THROTTLE', `3')dnl
dnl #
dnl # The -t option will retry delivery if e.g. the user runs over his quota.
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
dnl #
dnl # For using Cyrus-IMAPd as POP3/IMAP server through LMTP delivery uncomment
dnl # the following 2 definitions and activate below in the MAILER section the
dnl # cyrusv2 mailer.
dnl #
dnl define(`confLOCAL_MAILER', `cyrusv2')dnl
dnl define(`CYRUSV2_MAILER_ARGS', `FILE /var/lib/imap/socket/lmtp')dnl
dnl #
dnl # The following causes sendmail to only listen on the IPv4 loopback address
dnl # 127.0.0.1 and not on any other network devices. Remove the loopback
dnl # address restriction to accept email from the internet or intranet.
dnl #
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
dnl #
dnl # The following causes sendmail to additionally listen to port 587 for
dnl # mail from MUAs that authenticate. Roaming users who can't reach their
dnl # preferred sendmail daemon due to port 25 being blocked or redirected find
dnl # this useful.
dnl #
dnl DAEMON_OPTIONS(`Port=submission, Name=MSA, M=Ea')dnl
dnl #
dnl # The following causes sendmail to additionally listen to port 465, but
dnl # starting immediately in TLS mode upon connecting. Port 25 or 587 followed
dnl # by STARTTLS is preferred, but roaming clients using Outlook Express can't
dnl # do STARTTLS on ports other than 25. Mozilla Mail can ONLY use STARTTLS
dnl # and doesn't support the deprecated smtps; Evolution <1.1.1 uses smtps
dnl # when SSL is enabled-- STARTTLS support is available in version 1.1.1.
dnl #
dnl # For this to work your OpenSSL certificates must be configured.
dnl #
dnl DAEMON_OPTIONS(`Port=smtps, Name=TLSMTA, M=s')dnl
dnl #
dnl # The following causes sendmail to additionally listen on the IPv6 loopback
dnl # device. Remove the loopback address restriction listen to the network..
dnl #
dnl DAEMON_OPTIONS(`port=smtp,Addr=::1, Name=MTA-v6, Family=inet6')dnl
dnl #
dnl # enable both ipv6 and ipv4 in sendmail:
dnl #
dnl DAEMON_OPTIONS(`Name=MTA-v4, Family=inet, Name=MTA-v6, Family=inet6')
dnl #
dnl # We strongly recommend not accepting unresolvable domains if you want to
dnl # protect yourself from spam. However, the laptop and users on computers
dnl # that do not have 24x7 DNS do need this.
dnl #
FEATURE(`accept_unresolvable_domains')dnl
FEATURE(nocanonify)dnl
dnl #
dnl FEATURE(`relay_based_on_MX')dnl
dnl #
dnl # Also accept email sent to "localhost.localdomain" as local email.
dnl #
LOCAL_DOMAIN(`localhost.localdomain')dnl
dnl #
dnl # The following example makes mail from this host and any additional
dnl # specified domains appear to be sent from mydomain.com
dnl #
dnl MASQUERADE_AS(`common.oper')dnl
dnl #
dnl # masquerade not just the headers, but the envelope as well
dnl #
dnl FEATURE(masquerade_envelope)dnl
dnl #
dnl # masquerade not just @mydomainalias.com, but @*.mydomainalias.com as well
dnl #
dnl FEATURE(masquerade_entire_domain)dnl
dnl #
dnl MASQUERADE_DOMAIN(localhost)dnl
dnl MASQUERADE_DOMAIN(localhost.localdomain)dnl
dnl MASQUERADE_DOMAIN(oper)dnl
dnl MASQUERADE_DOMAIN(mydomain.lan)dnl
MAILER(smtp)dnl
MAILER(procmail)dnl
dnl MAILER(cyrusv2)dnl

> Sep 2 17:50:34 hostname sendmail[770878]: 182HoYH3770878: to=name@internet.domain.com, delay=00:00:00,
> mailer=relay, pri=30015, dsn=4.4.3, stat=queued
^^^^^^^^^^^^^^^^^^

So the mail stays in the (submission) queue due to a DNS problem. If your
system can't resolve names, take a look at the docs how to disable DNS lookups.

> internet.domain.com: Name server timeout
> name@internet.domain.com... Transient parse error -- message queued for future delivery
> name@internet.domain.com... queued

> The command 1 does not send the e-mail and nothing stays in queue. The command 2 sends out the e-mail which

See above: check the submission queue.

> arrives to my account. Commands 3 and 4 do not get the e-mails out, but they enter the queue.

> /etc/sendmail.mc file:

oops, please do not include all those "dnl" lines (comments).
> define(`SMART_HOST', `[relay.public.dmz]')dnl

> FEATURE(`mailertable', `hash -o /etc/mail/mailertable.db')dnl
> FEATURE(`virtusertable', `hash -o /etc/mail/virtusertable.db')dnl

If you want to use those tables, do not use -o

> I also have another similar server with almost identical configuration, which send e-mail to a smart host.
> However, that server can resolve internet domains.

See above: without DNS you have to change your config,
e.g., op.*:
2.5. The Service Switch
It might be simpler to "fix" DNS lookups.

BTW: you might have to change submit.mc depending on your setup.

--
Note: please read the netiquette before posting. I will almost never
reply to top-postings which include a full copy of the previous
article(s) at the end because it's annoying, shows that the poster
is too lazy to trim his article, and it's wasting the time of all readers.
--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet?

On 9/2/21 3:12 AM, Marko Hrastovec wrote:
> I have a strange problem I don't know how to resolve.
>
> I have server in an internal network without internet access and with internal DNS for local network only. Only some servers have internet access and they use a DNS that can resolve also internet domains.
>
> One server with internet access is used to relay mails out of this network, and servers without internet access use that server as a relay. I configure SMART_HOST and nocanonify on servers without internet access, and until now this was usually enough.
>
> On the latest (Oracle Linux 8 with sendmail 8.15.2), mails that I send to internet addresses are not sent to the relay server. maillog reports that relay is "root@localhost", in this case. I also have an alias for root in /etc/aliases, which is an valid e-mail on internet. If I send an e-mail to root, sendmail uses the configured smart host, and mail gets out. Sending to the same address directly does not work.
>
> I do not need any other mails (than for root) from this server, but I am curious, why is this happening.
>
> Regards
> Marko
>

Is it possible that you need to regenerate the sendmail.cf from your .mc file?

Thanks for the help. I have resolved the issue, and I remember now that I had to do that in the past already. All I had to do was to add the following line to /etc/mail/submit.mc

define(`confDIRECT_SUBMISSION_MODIFIERS',`C')dnl

> It might be simpler to "fix" DNS lookups.

DNS is "fixed". I do not want for internal server to resolve internet domains. Internal network has its own domain scheme and servers are isolated from the outside.