Hi,
I am new to linux so please have patience with me 
i run Postfix 3.4.13 on Ubuntu 20.4 and i would like to upgrade Postfix to 3.5.9.
How do i do that?
If i run sudo apt-get update and sudo apt-get install postfix, i get:
postfix is already the newest version (3.4.13-0ubuntu1).
Regards
Thomas
You unfortunately have to wait for Ubuntu packages to be created.
You can use one of the following methods to install the latest version of a software on Ubuntu.
For Postfix, there’s no PPA, snap package or a trusted third-party software repository, so you need to compile the source code.
My recommendation is that you stay with the version in your current Ubuntu repository. Unless you are sure you need to use a feature that’s only available in the latest version, I don’t recommend upgrading Postfix to the latest version.
If you have an existing Postfix SMTP server, then one day you run sudo apt update, then sudo apt upgrade, and the system is going to upgrade Postfix, you might be prompted to choose a configuration type for Postfix again. This time you should choose No configuration to leave your current configuration file untouched.
