Aerc is recommended as one of the best email clients that run on your terminal. It is free and open-source software which is very powerful and extensible and is perfect for discerning hackers.
The above-listed command-line or terminal or text-based email clients are the best you can use on your Linux system, but many times, you can only find out good features and performance attributes of an application after testing it.
Therefore, you can give all of them a try and choose which one to use, that is in case you are a command-line addict, who does not use GUIs so much. Importantly, you can also let us know of any other command-line email clients that you think deserve to appear in the list above