Sendmail is the regular email routing application that serves the purpose of sending mails. This offers several methods in delivering the mails, many other mails like Simple Transfer Mail Protocol. It was started when Internet is started. Many improvements were done in Security features that helps in preventing any abuse. Sendmail is used with Command line by giving the Subject, From and To addresses. Good number of positions is available for the candidates. Good knowledge on Sendmail, unix, perl cgi scripting will boost your confidence. Follow our Wisdomjobs page for Sendmail job interview questions and answers page to get through your job interview successfully in first attempt. Interview questions are exclusively designed for job seekers to assist them in clearing interviews.
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.
service sendmail restart
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.
List of users that can send email as other users without a warning including system users such as apache for the Apache HTTP Server.
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_fileâ€™) option must be enabled in the sendmail.mc file for this file to be referenced.
/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.
Yes, Sendmail can be configured to encrypt email sent and received using SSL (secure sockets layer).
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.
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.
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
Use "sendmail -bt -d0" command to check the sendmail compiler options. If sendmail was not compiled with LDAP support, recompile and install sendmail.
Add an ALIAS FILE define, containing the string ldap to the sendmail configuration.
# Set the LDAP cluster value
define(`conf LDAP CLUSTER', `wrotethebook.com')
# Tel sendmail that aliases are available via LDAP
define(`ALIAS FILE', `ldap:')
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.
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
dnl Users whose mail is not passed to the mail hub
Rebuild and reinstall sendmail.cf, and then restart sendmail.
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
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
Rebuild and reinstall sendmail.cf, and then restart sendmail.
we will make the changes only in the sendmail.mc file, and the changes will be moved into the sendmail.cf file for us.
Question 17. 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?
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
or If you are using a PHP based webmail application like SquirrelMail, you can adjust the max file size in php.ini file.
post_max_size = 50M
upload_max_filesize = 50M
memory_limit = 64M
Clamav-Milter is a tool to integrate sendmail and clamAV antivirus.
milter.conf and clamav-milter
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
The /etc/mail/ directory contain all the Sendmail configuration files, with sendmail.cf and submit.cf being the main configuration files.
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.
m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
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