I've recently gained employment as a web developer with a small company. What they neglected to tell me upon hire was that I would be administrating the server along with my other daily duties. Now, truth be told, I'm not clueless when it comes to these things, but this is my first rodeo working with a rack server/console..

However, I'm confident that I will be able to work through any solutions you provide.

Short Description:

When a customer places an order via our (Magento CE 1.8.1.0) website, a copy of said order is supposed to be BCC'd to our sales manager. I say supposed because this was a working feature before the old administrator left.

Long Description:

Shortly after I started, we had a server crash which required a server restart. After restart, we noticed a few features on our site weren't working, but all those have been cleaned up except this one. I had to create an account on our server for root access.

When a customer places an order, our sites software (Magento CE 1.8.1.0) is configured to BCC the customers order email to our sales manager. We use a Microsoft Exchange 2007 Server for our mail, which is hosted on a different machine (in-house) that I don't have access to ATM, but I'm sure I could if needed. As far as I can tell, all other external emails work.. Only INTERNAL email addresses fail to deliver. I know this because I've also tested my own internal address via our website. I set up an account with an internal email, made a test order, and never received the email. I changed my email for the account to an external GMail account, and received emails as expected. Let's dive into the logs and config's.

For privacy/security reasons, names have been changed to the following:

domain.com    = Our Top Level Domain.
email.local   = Our Exchange Server.
example.com   = ANY other TLD.
OLDadmin      = Our previous Server Administrator.
NEWadmin      = Me.
SALES@        = Our Sales Manager.
Customer#     = A Customer. 

Here's a list of the programs and config files used that hold relevant for this issue:

Server:

> [root@www ~]# cat /etc/centos-release
CentOS release 6.3 (final)

Sendmail:

> [root@www ~]# sendmail -d0.1 -bt < /dev/null
Version 8.14.4

========SYSTEM IDENTITY (after readcf)========
(short domain name)     $w = domain
(canonical domain name) $j = domain.com
(subdomain name)        $m = com
(node name)             $k = www.domain.com

> [root@www ~]# rpm -qa | grep -i sendmail
sendmail-cf-8.14.4-8.e16.noarch
sendmail-8.14-4-8.e16.x86_64

nslookup:

> [root@www ~]# nslookup email.local
Name:       email.local
Address:    192.168.1.50

hostname:

> [root@www ~]# hostname
www.domain.com

/etc/mail/access:

> [root@www ~]# vi /etc/mail/access
Connect:localhost.localdomain       RELAY
Connect:localhost                   RELAY
Connect:127.0.0.1                   RELAY

/etc/mail/domaintable:

> [root@www ~]# vi /etc/mail/domaintable
#

/etc/mail/local-host-names:

> [root@www ~]# vi /etc/mail/local-host-names
#

/etc/mail/mailertable:

> [root@www ~]# vi /etc/mail/mailertable
#

/etc/mail/sendmail.cf:

> [root@www ~]# vi /etc/mail/sendmail.cf

######################################################################
#####
#####   DO NOT EDIT THIS FILE!  Only edit the source .mc file.
#####
######################################################################
######################################################################

#####  $Id: cfhead.m4,v 8.120 2009/01/23 22:39:21 ca Exp $  #####
#####  $Id: cf.m4,v 8.32 1999/02/07 07:26:14 gshapiro Exp $  #####
#####  setup for linux  #####
#####  $Id: linux.m4,v 8.13 2000/09/17 17:30:00 gshapiro Exp $  #####



#####  $Id: local_procmail.m4,v 8.22 2002/11/17 04:24:19 ca Exp $  #####


#####  $Id: no_default_msa.m4,v 8.2 2001/02/14 05:03:22 gshapiro Exp $  #####

#####  $Id: smrsh.m4,v 8.14 1999/11/18 05:06:23 ca Exp $  #####

#####  $Id: mailertable.m4,v 8.25 2002/06/27 23:23:57 gshapiro Exp $  #####

#####  $Id: virtusertable.m4,v 8.23 2002/06/27 23:23:57 gshapiro Exp $  #####

#####  $Id: redirect.m4,v 8.15 1999/08/06 01:47:36 gshapiro Exp $  #####

#####  $Id: always_add_domain.m4,v 8.11 2000/09/12 22:00:53 ca Exp $  #####

#####  $Id: use_cw_file.m4,v 8.11 2001/08/26 20:58:57 gshapiro Exp $  #####


#####  $Id: use_ct_file.m4,v 8.11 2001/08/26 20:58:57 gshapiro Exp $  #####


#####  $Id: local_procmail.m4,v 8.22 2002/11/17 04:24:19 ca Exp $  #####

#####  $Id: access_db.m4,v 8.27 2006/07/06 21:10:10 ca Exp $  #####

#####  $Id: blacklist_recipients.m4,v 8.13 1999/04/02 02:25:13 gshapiro Exp $  #####

#####  $Id: accept_unresolvable_domains.m4,v 8.10 1999/02/07 07:26:07 gshapiro Exp $  #####

#####  $Id: masquerade_envelope.m4,v 8.9 1999/02/07 07:26:10 gshapiro Exp $  #####

#####  $Id: masquerade_entire_domain.m4,v 8.9 1999/02/07 07:26:10 gshapiro Exp $  #####


#####  $Id: proto.m4,v 8.741 2009/12/11 00:04:53 ca Exp $  #####

# level 10 config file format
V10/Berkeley

# override file safeties - setting this option compromises system security,
# addressing the actual file configuration problem is preferred
# need to set this before any file actions are encountered in the cf file
#O DontBlameSendmail=safe

# default LDAP map specification
# need to set this now before any LDAP maps are defined
#O LDAPDefaultSpec=-h localhost

##################
#   local info   #
##################

# my LDAP cluster
# need to set this before any LDAP lookups are done (including classes)
#D{sendmailMTACluster}$m

Cwlocalhost
# file containing names of hosts for which we receive email
Fw/etc/mail/local-host-names

# my official domain name
# ... define this only if sendmail cannot automatically determine your domain
#Dj$w.Foo.COM

# host/domain names ending with a token in class P are canonical
CP.

# "Smart" relay host (may be null)
DSemail.local


# operators that cannot be in local usernames (i.e., network indicators)
CO @ % !

# a class with just dot (for identifying canonical names)
C..

# a class with just a left bracket (for identifying domain literals)
C[[

# access_db acceptance class
C{Accept}OK RELAY


C{ResOk}OKR


# Hosts for which relaying is permitted ($=R)
FR-o /etc/mail/relay-domains

# arithmetic map
Karith arith
# macro storage map
Kmacro macro
# possible values for TLS_connection in access map
C{Tls}VERIFY ENCR

# who I send unqualified names to if FEATURE(stickyhost) is used
# (null means deliver locally)
DRemail.local.

# who gets all local email traffic
# ($R has precedence for unqualified names if FEATURE(stickyhost) is used)
DHemail.local.

# dequoting map
Kdequote dequote

# class E: names that should be exposed as from this host, even if we masquerade
# class L: names that should be delivered locally, even if we have a relay
# class M: domains that should be converted to $M
# class N: domains that should not be converted to $M
#CL root
C{E}root
C{w}localhost.localdomain
C{M}domain.com

# who I masquerade as (null for no masquerading) (see also $=M)
DMdomain.com

# my name for error messages
DnMAILER-DAEMON


# Mailer table (overriding domains)
Kmailertable hash -o /etc/mail/mailertable.db

# Virtual user table (maps incoming users)
Kvirtuser hash -o /etc/mail/virtusertable.db

CPREDIRECT

# Access list database (for spam stomping)
Kaccess hash -T<TMPF> -o /etc/mail/access.db

# Configuration version number
DZ8.14.4    

/etc/mail/sendmail.mc:

> [root@www ~]# vi /etc/mail/sendmail.mc

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', `email.local')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 # 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 # Rudimentary information on creating certificates for sendmail TLS:
dnl #     cd /etc/pki/tls/certs; make sendmail.pem
dnl # Complete usage:
dnl #     make -C /etc/pki/tls/certs usage
dnl #
dnl define(`confCACERT_PATH', `/etc/pki/tls/certs')dnl
dnl define(`confCACERT', `/etc/pki/tls/certs/ca-bundle.crt')dnl
dnl define(`confSERVER_CERT', `/etc/pki/tls/certs/sendmail.pem')dnl
dnl define(`confSERVER_KEY', `/etc/pki/tls/certs/sendmail.pem')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 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
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 #
MASQUERADE_AS(`domain.com')dnl
dnl #
dnl # masquerade not just the headers, but the envelope as well
dnl
FEATURE(masquerade_envelope)dnl
dnl #
dnl # masquerade not just @mydomainalias.com, but @*.mydomainalias.com as well
dnl #
FEATURE(masquerade_entire_domain)dnl
dnl #
MASQUERADE_DOMAIN(domain.com)dnl
dnl MASQUERADE_DOMAIN(localhost.localdomain)dnl
dnl MASQUERADE_DOMAIN(mydomainalias.com)dnl
dnl MASQUERADE_DOMAIN(mydomain.lan)dnl
MAILER(smtp)dnl
MAILER(procmail)dnl
dnl MAILER(cyrusv2)dnl

/etc/mail/trusted-users:

> [root@www ~]# vi /etc/mail/trusted-users
#

/etc/mail/virtusertable:

> [root@www ~]# vi /etc/mail/virtusertable
[email protected] [email protected]
[email protected] [email protected]

/etc/hosts:

> [root@www ~]# vi /etc/hosts
127.0.0.1       localhost.localdomain   localhost
::1             localhost6.localdomain6 localhost6
192.168.1.50    email.local

---

I've only included the "local info" part of sendmail.cf, to save space. If there are any files that I've missed, please advise so I may produce them.

Now that that's out of the way, lets look at some entries from /var/log/maillog. The first entry is from an order BEFORE the crash, when the site was working as expected.

##Order 200005374 Aug 5, 2014 7:06:38 AM##
Aug  5 07:06:39 www sendmail[26149]: s75C6dqB026149: from=OLDadmin, size=11091, class=0, nrcpts=2, msgid=<[email protected]>, relay=OLDadmin@localhost
Aug  5 07:06:39 www sendmail[26150]: s75C6dXe026150: from=<[email protected]>, size=11257, class=0, nrcpts=2, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Aug  5 07:06:39 www sendmail[26149]: s75C6dqB026149: [email protected],=?utf-8?B?dGhvbWFzICBHaWxsZXNwaWU=?= <[email protected]>, ctladdr=OLDadmin (501/501), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=71091, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75C6dXe026150 Message accepted for delivery)
Aug  5 07:06:40 www sendmail[26152]: s75C6dXe026150: to=<[email protected]>,<[email protected]>, delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=161257, relay=email.local. [192.168.1.50], dsn=2.0.0, stat=Sent ( <[email protected]> Queued mail for delivery)

This next entry from maillog is from an order AFTER the crash.

##Order 200005375 Aug 5, 2014 9:45:25 AM##
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4O030021: from=OLDadmin, size=11344, class=0, nrcpts=2, msgid=<[email protected]>, relay=OLDadmin@localhost
Aug  5 09:45:26 www sendmail[30022]: s75EjQm1030022: <[email protected]>... User unknown
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4O030021: [email protected], ctladdr=OLDadmin (501/501), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=71344, relay=[127.0.0.1] [127.0.0.1], dsn=5.1.1, stat=User unknown
Aug  5 09:45:26 www sendmail[30022]: s75EjQm1030022: from=<[email protected]>, size=11500, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4O030021: to==?utf-8?B?S2VubmV0aCBCaWViZXI=?= <[email protected]>, ctladdr=OLDadmin (501/501), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=71344, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75EjQm1030022 Message accepted for delivery)
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4O030021: s75EjQ4P030021: DSN: User unknown
Aug  5 09:45:26 www sendmail[30022]: s75EjQm3030022: <[email protected]>... User unknown
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4P030021: to=OLDadmin, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=42368, relay=[127.0.0.1] [127.0.0.1], dsn=5.1.1, stat=User unknown
Aug  5 09:45:26 www sendmail[30022]: s75EjQm3030022: from=<>, size=12368, class=0, nrcpts=0, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4P030021: s75EjQ4Q030021: return to sender: User unknown
Aug  5 09:45:26 www sendmail[30022]: s75EjQm5030022: from=<>, size=14845, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Aug  5 09:45:26 www sendmail[30021]: s75EjQ4Q030021: to=postmaster, delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=43392, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75EjQm5030022 Message accepted for delivery)
Aug  5 09:45:26 www sendmail[30025]: s75EjQm5030022: to=root, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=45053, dsn=2.0.0, stat=Sent
Aug  5 09:45:27 www sendmail[30024]: s75EjQm1030022: to=<[email protected]>, delay=00:00:01, xdelay=00:00:01, mailer=relay, pri=131500, relay=email.local. [192.168.1.50], dsn=2.0.0, stat=Sent ( <[email protected]> Queued mail for delivery)

To add a little more, I think I've pinpointed the actual crash event.

##THE CRASH##
Aug  5 09:39:46 www sendmail[3251]: restarting /usr/sbin/sendmail due to signal
Aug  5 09:39:46 www sm-msp-queue[3260]: restarting /usr/sbin/sendmail due to signal
Aug  5 09:39:46 www sm-msp-queue[29370]: starting daemon (8.14.4): queueing@01:00:00
Aug  5 09:39:47 www sendmail[29372]: starting daemon (8.14.4): SMTP+queueing@01:00:00
Aug  5 09:40:02 www sendmail[29465]: s75Ee2vT029465: Authentication-Warning: www.domain.com: OLDadmin set sender to root using -f
Aug  5 09:40:02 www sendmail[29464]: s75Ee2IF029464: Authentication-Warning: www.domain.com: OLDadmin set sender to root using -f
Aug  5 09:40:02 www sendmail[29465]: s75Ee2vT029465: from=root, size=1426, class=0, nrcpts=1, msgid=<[email protected]>, relay=OLDadmin@localhost
Aug  5 09:40:02 www sendmail[29464]: s75Ee2IF029464: from=root, size=1426, class=0, nrcpts=1, msgid=<[email protected]>, relay=OLDadmin@localhost
Aug  5 09:40:02 www sendmail[29466]: s75Ee23t029466: from=<[email protected]>, size=1784, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Aug  5 09:40:02 www sendmail[29466]: s75Ee23t029466: to=<[email protected]>, delay=00:00:00, mailer=local, pri=31784, dsn=4.4.3, stat=queued
Aug  5 09:40:02 www sendmail[29467]: s75Ee2wh029467: from=<[email protected]>, size=1784, class=0, nrcpts=1, msgid=<[email protected]>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
Aug  5 09:40:02 www sendmail[29467]: s75Ee2wh029467: to=<[email protected]>, delay=00:00:00, mailer=local, pri=31784, dsn=4.4.3, stat=queued
Aug  5 09:40:02 www sendmail[29464]: s75Ee2IF029464: to=OLDadmin, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=31426, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75Ee23t029466 Message accepted for delivery)
Aug  5 09:40:02 www sendmail[29465]: s75Ee2vT029465: to=OLDadmin, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=31426, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (s75Ee2wh029467 Message accepted for delivery)
Aug  5 09:40:06 www sm-msp-queue[29370]: restarting /usr/sbin/sendmail due to signal
Aug  5 09:40:06 www sendmail[29372]: restarting /usr/sbin/sendmail due to signal
Aug  5 09:40:06 www sm-msp-queue[29888]: starting daemon (8.14.4): queueing@01:00:00
Aug  5 09:40:06 www sendmail[29890]: starting daemon (8.14.4): SMTP+queueing@01:00:00
Aug  5 09:40:06 www sendmail[29891]: s75Ee23t029466: to=<[email protected]>, delay=00:00:04, mailer=local, pri=121784, dsn=5.1.1, stat=User unknown
Aug  5 09:40:06 www sendmail[29891]: s75Ee23t029466: s75Ee6xY029891: DSN: User unknown
Aug  5 09:40:06 www sendmail[29891]: s75Ee6xY029891: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=33035, dsn=2.0.0, stat=Sent
Aug  5 09:40:06 www sendmail[29891]: s75Ee2wh029467: to=<[email protected]>, delay=00:00:04, mailer=local, pri=121784, dsn=5.1.1, stat=User unknown
Aug  5 09:40:06 www sendmail[29891]: s75Ee2wh029467: s75Ee6xZ029891: DSN: User unknown
Aug  5 09:40:06 www sendmail[29891]: s75Ee6xZ029891: to=<[email protected]>, delay=00:00:00, xdelay=00:00:00, mailer=local, pri=33035, dsn=2.0.0, stat=Sent

Something to note about the maillog's:

1. Before the crash, the msgid included localhost.localdomain; after the crash it's been domain.com.

Thanks to all who take the time to read and look into this issue. I appreciate it and look forward to tackling this issue together.