How to Install Sendmail Service on CentOS 6.5

In web hosting, the ability to effectively manage and configure your server is crucial. One such task that often arises is the installation and configuration of the Sendmail service, particularly on CentOS 6.5 systems. While CentOS 6.5 comes with the Postfix SMTP service by default, there may be instances where you’d prefer to use Sendmail instead. Both services serve the same purpose – providing SMTP email transport service and functioning as an email relay on your Linux system. However, each has its unique features and benefits.

If you’re looking for a guide on how to install Sendmail on CentOS 6.5, you’ve come to the right place. This tutorial will walk you through the process step-by-step, ensuring you have a thorough understanding of each stage.

Installing Sendmail on CentOS 6.5

The first step in setting up Sendmail on your CentOS 6.5 system is to install the service. This can be done using the YUM package manager, which is included by default in CentOS. Here’s how to do it:

[root@centos6.5 ~]# yum install sendmail -y

This command will initiate the installation process. During this process, YUM will resolve any dependencies required by Sendmail. In this case, it will install the ‘procmail’ and ‘hesiod’ packages alongside Sendmail. Once the installation is complete, you should see a ‘Complete!’ message.

Example:

[root@centos6.5 ~]# yum install sendmail -y
..
..
..
..
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package sendmail.x86_64 0:8.14.4-8.el6 will be installed
--> Processing Dependency: procmail for package: sendmail-8.14.4-8.el6.x86_64
--> Processing Dependency: libhesiod.so.0()(64bit) for package: sendmail-8.14.4-8.el6.x86_64
--> Running transaction check
---> Package hesiod.x86_64 0:3.1.0-19.el6 will be installed
---> Package procmail.x86_64 0:3.22-25.1.el6 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

====================================================================================================
 Package                Arch                 Version                       Repository          Size
====================================================================================================
Installing:
 sendmail               x86_64               8.14.4-8.el6                  base               717 k
Installing for dependencies:
 hesiod                 x86_64               3.1.0-19.el6                  base                20 k
 procmail               x86_64               3.22-25.1.el6                 base               163 k

Transaction Summary
====================================================================================================
Install       3 Package(s)

Total download size: 900 k
Installed size: 1.9 M
Downloading Packages:
(1/3): hesiod-3.1.0-19.el6.x86_64.rpm                                        |  20 kB     00:00
(2/3): procmail-3.22-25.1.el6.x86_64.rpm                                     | 163 kB     00:00
(3/3): sendmail-8.14.4-8.el6.x86_64.rpm                                      | 717 kB     00:06
----------------------------------------------------------------------------------------------------
Total                                                               117 kB/s | 900 kB     00:07
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : procmail-3.22-25.1.el6.x86_64                                                    1/3
  Installing : hesiod-3.1.0-19.el6.x86_64                                                       2/3
  Installing : sendmail-8.14.4-8.el6.x86_64                                                     3/3
  Verifying  : hesiod-3.1.0-19.el6.x86_64                                                       1/3
  Verifying  : procmail-3.22-25.1.el6.x86_64                                                    2/3
  Verifying  : sendmail-8.14.4-8.el6.x86_64                                                     3/3

Installed:
  sendmail.x86_64 0:8.14.4-8.el6

Dependency Installed:
  hesiod.x86_64 0:3.1.0-19.el6                    procmail.x86_64 0:3.22-25.1.el6

Complete!

Starting the Sendmail Service

With Sendmail installed, the next step is to start the service. This can be done with the following command:

[root@centos6.5 ~]# service sendmail start

Upon running this command, you should see an ‘[ OK ]’ message next to both ‘Starting sendmail:’ and ‘Starting sm-client:’, indicating that the service has started successfully.

Example:

[root@centos6.5 ~]# service sendmail start
Starting sendmail:                                         [  OK  ]
Starting sm-client:                                        [  OK  ]

Testing Sendmail

After starting the Sendmail service, it’s a good idea to test it to ensure it’s running correctly. One way to do this is by checking if Sendmail is responding on port 25, which is the standard port for SMTP services. This can be done using the ‘telnet’ command:

[root@centos6.5 ~]# telnet localhost 25
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 centos6.5.webhostinggeeks.local ESMTP Sendmail 8.14.4/8.14.4; Sun, 10 Aug 2014 20:48:52 +0800

This command attempts to connect to the localhost on port 25. If Sendmail is running correctly, you should see a ‘Connected to localhost.’ message, followed by a 220 status code from the Sendmail service.

Commands Mentioned

• yum install sendmail -y – This command installs the Sendmail service on your CentOS 6.5 system.
• service sendmail start – This command starts the Sendmail service.
• telnet localhost 25 – This command tests if Sendmail is responding on port 25, the standard port for SMTP services.

Conclusion

Managing a web server involves a myriad of tasks, and understanding how to install and configure services like Sendmail is a crucial part of this process. This tutorial has provided a step-by-step guide on how to install the Sendmail service on CentOS 6.5, start the service, and test its functionality. By following these steps, you can ensure that your server is equipped to handle SMTP email transport effectively.

Remember, this is just one aspect of server management. There are many other tasks and services that you may need to handle, depending on your specific needs and the requirements of your server.

For more guides and tutorials on server management and web hosting, be sure to check out our other articles. Whether you’re interested in learning about different web servers like Apache, Nginx, and LiteSpeed, or you want to understand the differences between dedicated, VPS, cloud, and shared hosting, we’ve got you covered.

FAQs

1. What is the difference between Sendmail and Postfix?

   Sendmail and Postfix are both Mail Transfer Agents (MTAs) that serve to route and deliver email on a Linux system. While they perform similar functions, they differ in terms of configuration and performance. Sendmail, being one of the oldest MTAs, is known for its wide range of features but has a complex configuration. Postfix, on the other hand, is newer, easier to configure, and is designed with a strong focus on security.

2. How can I check if Sendmail is running on my server?

   You can check if Sendmail is running by using the ‘telnet’ command to connect to the localhost on port 25, which is the standard port for SMTP services. If Sendmail is running correctly, you should see a ‘Connected to localhost.’ message, followed by a 220 status code from the Sendmail service.

3. What are the dependencies for Sendmail?

   When installing Sendmail using the YUM package manager, it will automatically resolve and install any dependencies required by Sendmail. In this case, it installs the ‘procmail’ and ‘hesiod’ packages alongside Sendmail.

4. How do I start the Sendmail service?

   You can start the Sendmail service by running the command ‘service sendmail start’ in your terminal. Upon running this command, you should see an ‘[ OK ]’ message next to both ‘Starting sendmail:’ and ‘Starting sm-client:’, indicating that the service has started successfully.

5. What is the purpose of the Sendmail service?

   Sendmail is a Mail Transfer Agent (MTA) that serves to route and deliver email on a Linux system. It provides SMTP email transport service and functions as an email relay on your system. This means it accepts email from users and routes it to the intended recipient, which can be on the same system or on another system on the network.