Sendmail Interview Questions & Answers part 1
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: – 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_fileâ€™) 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 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.