I want to delete mail hosting, but not lose the mail in the Mail Add-On

I want to delete mail hosting, but not lose the mail in the Mail Add-On

Before I do something that is irreversible:

What I want to do:

1) cancel Mail Hosting - I want to do that on another server/service
2) I do want to keep the Mail Add-on and configure the mail to receive from that other server

BUT,

I do NOT want to lose the emails that are already in the Mail Add-on under that domain name because they are all stored in folders, etc.

Do I need to export all of those emails to make sure they don't disappear?  Or will I be able to somehow configure that POP account that already exists with the new server info?

My problem is when I go to the Mail settings, that particular mail account hosted on Zoho doesn't have any option on the settings for the pop/smtp settings... so I'm concerned once I cancel the hosting, that mail account disappears too.

Thanks for any help.