I used to use linux then I went back to windows now I have this laptop that is only used for important emails and web browsing. but the windows seems to be straining this hardware so I am wanting to go back to Linux ( at least on this laptop) .
the email client on windows I am using is called the bat and it shows that I can export my emails then installed a linux based email client then import those email to it. I am not sure if I can do this if so the bat email client exports to .msg .eml and UNIX mailbox. if it can be done will my emails look the same or will they be not like the originals emails?

They should look the same, if the Linux mail client has the same capabilities.

The only eventuality I can think of that might keep that from happening is your picking one for very few Linux email clients that does not handle HTML email, such as Claws and any of the command line email clients (Mutt, Alpine, and so on). There might be some minor variations based on available fonts, application window size, and the like.

Just my two cents.

I’m using Thunderbird on both Windows and Linux, using imap connections to several mail servers. Don’t have to migrate anything. Can even connect with Mail on my iPad and iPhone to those same servers. So that’s my recommendation: Thunderbird. Should be available in your distro’s repositories.

What kind of connection are you using with The Bat? (A client that I always block mail from, BTW...have never seen anything but spam from senders using it). If POP3, you’ll need to do whatever is documented to export your mail, then import according to the documentation of your chosen Linux client. Note that exporting/importing mail shouldn’t destroy anything in the bat, so if you don’t like what you see just try with a different Linux client.

If you’re using IMAP, connecting with a Linux client shouldn’t change anything.

this.
and if you're unsure, i think a modern email client defaults to IMAP nowadays.