Error while installing postfix on CentOS 6

I want to install postfix on CentOS 6 but I get the following error :

yum install postfix -y
Loaded plugins: fastestmirror
Setting up Install Process
Determining fastest mirrors
YumRepo Error: All mirror URLs are not using ftp, http[s] or file.
 Eg. Invalid release/repo/arch combination/
removing mirrorlist with no valid mirrors: /var/cache/yum/x86_64/6/base/mirrorlist.txt
Error: Cannot find a valid baseurl for repo: base

Can anyone tell me how to fix this ? Does it have anything to do with people saying CentOS 6 is dead ? Is there any fix ?

CentOS 6 went completely end of life on November 30. Therefore, you won't be able to patch, or install any new software.

The only exception to this would be if you were to convert your system to RHEL 6, and purchase Red Hat Extended Life Cycle Support.

I wouldn't even recommend that, however. You should upgrade to CentOS 7, or even CentOS 8 instead.

While CentOS 6 is truly dead, and the ultimate fix is upgrading, you can still install packages by using the Vault repositories as detailed here.

To quickly fix up your CentOS 6 so you can yum install things, run:

curl https://www.getpagespeed.com/files/centos6-eol.repo --output /etc/yum.repos.d/CentOS-Base.repo