Q: - How to start
sendmail server ?
service sendmail restart
Q: - On which ports
sendmail and senmail with SSL works ?
By default, Sendmail uses TCP and UDP port 25 for
non-encrypted transfers. If the Sendmail server is configured to use SSL for
encrypting email sent and received, it uses port 465.
Q: - Explain use of
"trusted-users" file ?
List of users that can send email as other users without a
warning including system users such as apache for the Apache HTTP Server.
Q: - Explain the use
of "local-host-names" file ?
If the email server should be known by different hostnames,
list the host- names in this file, one line per hostname. Any email sent to
addresses at these hostnames is treated as local mail. The FEATURE(`use_cw_fileĆ¢€™)
option must be enabled in the sendmail.mc file for this file to be referenced.
Q: - explain the use
of /etc/aliases file ?
/etc/aliases, can be used to redirect email from one user to
another. By default, it includes redirects for system accounts to the root
user. It can then be used to redirect all email for the root user to the user
account for the system administrator.
Q: - Can we use SSL
Encryption with Sendmail ?
Yes, Sendmail can be configured to encrypt email sent and
received using SSL (secure sockets layer)
Q: - What is Sendmail
?
Sendmail is an MTA, meaning it accepts email messages sent
to it using the SMTP proto- col and transports them to another MTA email server
until the messages reach their destinations. It also accepts email for the
local network and delivers them to local mail spools, one for each user.
Q: - What is the role
of MUA ?
An MUA (Mail User Agent) with access to the mailbox file,
directly or through a network file system, can read messages from the disk and
display them for the user. This is generally a console or webmail application
running on the server.
Q: - Which are the
important configuration files for Sendmail server ?
The /etc/mail/ directory contains all the Sendmail
configuration files, with sendmail.cf and submit.cf being the main
configuration files. The sendmail.cf file includes options for the mail
transmission agent and accepts SMTP connections for sending email. The
submit.cf file configures the mail submission program.
Q: - How to configure
sendmail to accept mail for local delivery that is addressed to other hosts?
Create a /etc/mail/local-host-names file. Put into that file
the hostnames and domain names for which sendmail should accept mail for local
delivery. Enter the names with one hostname or domain name per line. And also
make sure that Sendmail configuration file should contain
"use_cw_file" option.
dnl Load class $=w with other names for the local host
FEATURE(`use_cw_file')
Q: - When an
organization stores aliases on an LDAP server, how you will configure sendmail
to read aliases from the LDAP server?
Use "sendmail -bt -d0" command to check the
sendmail compiler options. If sendmail was not compiled with LDAP support,
recompile and reinstall sendmail.
Add an ALIAS_FILE define, containing the string ldap to the sendmail configuration.
# Set the LDAP cluster value
define(`confLDAP_CLUSTER', `wrotethebook.com')
# Tell sendmail that aliases are available via LDAP
define(`ALIAS_FILE', `ldap:')
Q: - How to forward
emails of a local user to external address?
Add an alias to the aliases file for each user whose mail
must be forwarded to another system. The recipient field of the alias entry
must be a full email address that includes the host part. After adding the
desired aliases, rebuild the aliases database file with the newaliases command.
Q: - You have been
asked to create a sendmail configuration that sends all local mail to a mail
hub, while directly delivering mail addressed to external systems.
Create a sendmail configuration containing the MAIL_HUB
define to identify the mail relay host for local mail. Use the LOCAL_USER
command to exempt the root user's mail from relaying.
dnl Define a relay server for local mail
define(`MAIL_HUB', `smtp.test.com')
dnl Users whose mail is not passed to the mail hub
LOCAL_USER(root)
Rebuild and reinstall sendmail.cf, and then restart
sendmail.
Q: - How to configure multiple mail queues?
mkdir /var/spool/mqueue/queue.1
mkdir /var/spool/mqueue/queue.2
mkdir /var/spool/mqueue/queue.3
chmod 700 /var/spool/mqueue/queue.1
chmod 700 /var/spool/mqueue/queue.2
chmod 700 /var/spool/mqueue/queue.3
Add the QUEUE_DIR define to the sendmail configuration to
use the new queue directories.
dnl Declare the queue directory path
define(`QUEUE_DIR', `/var/spool/mqueue/queue.*')
Q: - How to disable certain SMTP commands?
Add the confPRIVACY_FLAGS define to the sendmail
configuration to set Privacy Options that disable unwanted, optional SMTP
commands. Here we will disables the EXPN, VRFY, VERB, and ETRN commands.
dnl Disable EXPN, VRFY, VERB and ETRN
define(`confPRIVACY_FLAGS', `noexpn,novrfy,noverb,noetrn')
Rebuild and reinstall sendmail.cf, and then restart
sendmail.
Q: - In which
Sendmail configuration file we have to make changes?
we will make the changes only in the sendmail.mc file, and
the changes will be moved into the sendmail.cf file for us.
Q: - When Sendmail
dispatches your email, it places the servers hostname behind your username,
which becomes the "from address" in the email (ie.
user@mail.test.com).But we want to use the domain name and not the hostname?
define(`confDOMAIN_NAME', `test.com')dnl
FEATURE(`relay_entire_domain')dnl
Q: - What does /etc/mail/access
file contains?
The access database ("/etc/mail/access") is a list
of IP addresses and domainnames of allowable connections.
FEATURE(`access_db',`hash -T -o
/etc/mail/access.db')dnl
and cat
/etc/mail/access
localhost.localdomain RELAY
localhost RELAY
127.0.0.1 RELAY
192.168.0
RELAY
test.com RELAY
Q: - How to restrict sendmail
to sending a big file?
define(`confMAX_MESSAGE_SIZE',`52428800')dnl
or If you are using a PHP based webmail application like
SquirrelMail, you can adjust the max file size in php.ini file.
vi php.ini
post_max_size = 50M
upload_max_filesize = 50M
memory_limit = 64M
Q: - How to set 25
recipients for each email?
define(`confMAX_RCPTS_PER_MESSAGE',`50')dnl
Q: - Which antivirus
you have integrated with sendmail ?
ClaimAV
Q: - What is
Clamav-Milter?
Clamav-Milter is a tool to integrate sendmail and clamAV
antivirus.
Q: - Which
configuration files are required to integrate sendmail and ClaimAV antivirus?
milter.conf and clamav-milter
Q: - How to test
sendmail integration with ClaimAV?
grep Milter /var/log/maillog
You have to get following type of messages.
sendmail: Milter add: header: X-Virus-Scanned: ClamAV
version 0.88.2, clamav-milter version 0.88.2 on mail.test.com
sendmail: Milter add: header: X-Virus-Status: Clean
Q: - Which tool you
have used to block spamming?
SpamAssassin
Q: - What does
"/etc/mail/" directory contains?
The /etc/mail/ directory contain all the Sendmail
configuration files, with sendmail.cf and submit.cf being the main
configuration files.
Q: - Explain the use
of /etc/mail/relay-domains file?
The /etc/mail/relay-domains file is used to determine
domains from which it will relay mail. The contents of the relay-domains file
should be limited to those domains that can be trusted not to originate spam.
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