NETWORK - SENDMAIL

Sendmail

The sendmail command receives formatted text messages and routes the messages to one or more users.

/etc/mail/sendmail.cf   sendmail configurations, after modifications refresh -s sendmail
/var/spool/mqueue       mail queue, stores data and control files for messages (can store temporarily the mail here)
                        (if the mail queue becomes unresponsive run: sendmail -q -v (-q: force the queue to run, -v: verbose))
/usr/spool/mqueue       sendmail default logs are here (this is used, unless in syslog other dir is specified for mails)
/var/spool/mail/<user>  the user's mailbox resides here


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Configuring sendmail:

1. starting sendmail
lssrc -s sendmail                                           <--checking if it is runnig
startsrc -s sendmail -a "-bd -q30m"                         <--starting if it is needed (-bd: background, q30: queue processing interval)
vi /etc/rc.tcpip -> uncomment: start /usr/lib/sendmail      <--sendmail is started from this file after reboot


2. set mail relay server
vi /etc/mail/sendmail.cf
#DSmailer:relayhostname
DSaix1.domain.com                                            <--at DS line set a smarthost (probably an SMTP server) which can forward mails

3. refresh sendmail
refresh -s sendmail                                          <--refresh sendmail to activate new settings

4. testing sendmail

-with mail command (sender mailbox can't be set):
echo "This is a test mail"|mail -v -s "this is the subject" mail_address@anything.com
(if this does not work maybe your sender mailbox (e.g. root@hostname) is not accepted by mail relay server)
(sender mailbox cannot be set with mail command and it will show as an accepted message, but mail won't be forwarded)


-with telnet (sender mailbox is possible to set):
On aixmail we have set a working mailrelay, and we test this from aixdb2:
(doing telnet on aixmail to localhost works as well)

root@aixdb2: / # telnet aixmail 25                           <--telnet to port 25
Trying...
Connected to aixmail.fsc.uk.
Escape character is '^]'.
220 aixmail.fsc.uk ESMTP Sendmail Thu, 3 Nov 2011 15:45:05 GMT
helo aixmail                                                <--saying hello to mailserver (setting up the communication,'ehlo' works as well)
250 aixmail.fsc.uk Hello aixdb2.fsc.uk [10.200.200.22], pleased to meet you
mail from: something@anything.com                          <--sets sender mailbox (don't forget on mailrelay could be some restricions)
250 2.1.0 something@anything.com... Sender ok              (if "Bad sender address syntax", use <> at address, i.e. <something@ganything.com>
rcpt to: mail_address@anything.com                         <--setting up the destination address
250 2.1.5 mail_address@anything.com... Recipient ok
data                                                       <--after this the subject and the body of the mail will follow
354 Enter mail, end with "." on a line by itself
subject: test message                                      <--subject
this is a test message from aixdb2                         <--mail body
.                                                          <--end your mail with a "."
250 2.0.0 pA3Fj5mf586210 Message accepted for delivery
quit                                                       <--closes connection
221 2.0.0 aixmail.fsc.uk closing connection
Connection closed.

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CONFIGURATION HINTS for sendmail.cf file:
(after manipulating sendmail.cf don't forget refresh -s sendmail)

-MAILRELAY CONFIG:
Mailrelay (Smart relay host) can be set at DS line:

# "Smart" relay host (may be null)
DSmailrelaynew.domain.com
#DSmailrelayold.domain.com

----------

-DOMAIN REWRITING:
If you want all mails are being sent from a specific domain
(only domain name will be rewritten, user name won't be changed)

I added the needed domain at 2 places in config file:
at Dj line:
Djservices.domain.com

and at DM line:
# who I masquerade as (null for no masquerading)
DMservices.domain.com

(At the mailserver where you send the mails there can be restricions, which sender domains are accepted.)

----------

-USER and DOMAIN REWRITING:
If you want all mails are being sent from a given sender address (user and domain will be rewritten: user@domain)

Find the below section at SMTP Mailrelay specification part and I commented out (put #) at all the lines, except SEnvFromSMTP.
I added one more line at the end which contains the sender mail address.
(it is important to use tab for spacing!)

#####################################
###   SMTP Mailer specification   ###
#####################################

...
...
...


#
#  envelope sender rewriting
#
SEnvFromSMTP=11
#R$+                    $: $>PseudoToReal $1            sender/recipient common
#R$* :; <@>             $@                              list:; special case
#R$*                    $: $>MasqSMTP $1                qualify unqual'ed names
#R$+                    $: $>MasqEnv $1                 do masquerading
R$*                     $: user1@anydomain.com        do mask

(details on why you see different sender address in your mail program: http://utcc.utoronto.ca/usg/technotes/smtp-intro.html)

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These can be checked when there are problems:

- var/spool and /var/spool/mqueue group write rights may be needed


- lssrc -s sendmail (or ps -ef sendmail)


- lssrc -ls sendmail or mailstats
    root@aix20: /root # lssrc -ls sendmail
    Statistics from Tue Dec  7 12:05:47 2010
     M   msgsfr  bytes_from   msgsto    bytes_to  msgsrej msgsdis msgsqur  Mailer
     3        8          8K     1054     110084K        0       0       0  local
     4        0          0K        8          8K        0       0       0  smtp
    =====================================================================
     T        8          8K     1062     110092K        0       0       0
     C        0                    8                    0   

    msgsto: how many mail has been sent
    bytes_to: the size of all the sent messages
    msgsrej: messgaes rejected
    msgsdis: messages discarded

    local: sent mails to local users to /var/spool/mail/<user>
    smtp: sent mail to other hosts


- mailq
     it will show if mailq is processed or not
   
    root@aix20: /root # mailq
                /var/spool/mqueue (1 request)
    ----Q-ID---- --Size-- -----Q-Time----- ------------Sender/Recipient------------
    oB7AY7Qp909566       37 Tue Dec  7 11:34 root
                 (Deferred: local mailer (/bin/bellmail) exited with EX_TEMPFA)
                                         root
                Total requests: 1

    (It shows there are some problems as mailq is not processes, if it shows empty that is good)


- sendmail -v -q
    manually tests sendmail

    root@aix20: /root # sendmail -v -q
    Running /var/spool/mqueue/oB7AY7Qp909566 (sequence 1 of 1)
    root... Connecting to local...
    root... Deferred: local mailer (/bin/bellmail) exited with EX_TEMPFAIL

    (It shows there are some problems, if we receive no output, that would be good.)

- grep mail /etc/syslog.conf
    check syslog settings (if no mail line, then default line is valid for mail logs)
    mail.debug           /usr/spool/mqueue/syslog rotate size 1000k files 4


- sending a testmail (with mail or telnet)

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Basic mail server config with sendmail

0. # vi /etc/mail/sendmail.cf

1. Fw/etc/mail/local-host-names        <--uncomment local-host-names, it defines which domains the mail server will be responsible for.

2. FR-o /etc/mail/relay-domains        <--uncomment relay-domains, it defines which hosts are allowed to use this server as a mail relay.

3. DSmailserver.domain.com             <--set "Smart" relay host if needed (may be null)

If the mail server is behind a firewall, you will need port 25 open. Typically a mail server has direct access through the firewall. But if the mail server does not have direct access through the firewall, then it will need to point to another mail server that can. In this case the admin can append the hostname of the mail server after the "DS".

4. create /etc/mail/local-host-names database file

# vi /etc/mail/local-host-names
   examples:
   testdomain.com                      <--it contains all the domains that this mail server will be accepting mail for.
   somedomain.com

5. create /etc/mail/relay-domains database file

# vi /etc/mail/relay-domains
   examples:
   testsystem                          <--it contains all the hostnames, subnets or domains that will be allowed to use this server as a mail relay.
   testdomain.com
   10.1.1.1
   192.168

6. stopsrc -s sendmail                  <--stop sendmail
7. startsrc -s sendmail -a "-bd -q30m"    <--start sendmail

----------------------------------------------------

Warning: .cf file is out of date: sendmail AIX5.3/8.13.4 supports version 10, .cf file is version 9
root@aix20: /root # sendmail -v -q
Warning: .cf file is out of date: sendmail AIX5.3/8.13.4 supports version 10, .cf file is version 9
   
change V9 to V10 in sendmail.cf:
root@aix20: /root # vi /etc/mail/sendmail.cf
# level 9 config file format
V10/Berkeley

----------------------------------------------------

mailstats: /etc/mail/statistics: No such file or directory

root@aixdb1: / # lssrc -ls sendmail
mailstats: /etc/mail/statistics: No such file or directory

root@aixdb1: / # touch /etc/mail/statistics

----------------------------------------------------

HOW TO CLEAR MAILS:
    1. mail             shows the user's mails
    2. d 1-1326         deletes the user's mail form the first to the 1326th
    3. h                shows the headers of the mails (or the remainders if we deleted some)
    4. q                quits

----------------------------------------------------

Deferred: local mailer (/bin/bellmail) exited with EX_TEMPFA

solution: http://aixblogs.blogspot.com/2009_04_01_archive.html

check permissions of /var/spool/mail and /var/spool/mqueue
!!!check also /var/spool


these are good settings:
root@aix20: /root # ls -ld /var/spool/mail
drwxrwxr-x    2 bin      mail            256 Dec 07 12:45 /var/spool/mail
root@aix20: /root # ls -ld /var/spool/mqueue

drwxrwx---    2 root     system         4096 Dec 07 12:45 /var/spool/mqueue

root@aix20: /root # ls -ld /var/spool
drwxrwxr-x   12 bin      bin            4096 Dec 07 12:46 /var/spool

----------------------------------------------------

gethostbyaddr(IPv6:::1) failed: 1

In syslog sendmail can log this warning message: "gethostbyaddr(IPv6:::1) failed: 1"

This is because IPv6 is enabled, and sendmail tries to do an IPv6 lookup on the IPv6 loopback interface (::1). This lookup is failing and the gethostbyaddr warning is logged by syslogd.

1. add ::1 loopback to /etc/hosts
root@aix20: /root # vi /etc/hosts
::1 loopback localhost

(Future releases of AIX will automatically include this entry in the /etc/hosts file)

2.add bind4 to /etc/netsvc.conf:
hosts=local,bind4