How to save emails on Macbook pro to Passport Ultra?

I’ve searched online and am so confused. Please can you tell me how to save selected emails from my Macbook pro to my Passport Ultra external hard drive…
I’ll be very grateful if you can help me.
Thank you - a thousand times.

First, you have posted your question in the My Passport Wireless -forum. A more suitable place for you to ask about the Ultra may be at
https://community.wd.com/c/wd-external-drives/external-drives-for-mac

Second, If you need to save the odd email from Mail, the easiest way is to select it in Mail then drag it to the drive of your choosing.
If you want to save more emails you could export a whole mailbox to the drive of your choosing. Select mailbox, right click, choose export.

Hello,

I have moved the post to the correct board.

Thank you for your answer Hamlet. and for putting my post on the correct board.
I have folders in Mail but when I export them to WD Ultra the emails don’t show up there.
What appears are three choices:
info.plist
mbox
table of contents
and when I open any of those, there is just “computer language” and no emails at all.
No doubt it’s a simple fix and thank you if you can help, again.