I don't understand. You can create hundreds of SMTP servers, but they're useless if there is no account to affix them to. Yes, you can create extra SMTP servers at account settings and link to Outlook Servers (SMTP) and click the Add button. But why?

Checked and found that I am running an older version.

I looked for a white paper on how to migrate from 115, but have not located one.

Are you able to point me to an article?

I think all you need do is click help>about and see if 128 is available for you.

I am running Mint. I am able to download and install 128.

Trying to determine how to move/point/import my existing mail

To get appropriate Linux help, I suggest you share from where you are getting the update, such as Flatpak. My awareness, as a Linux newbie, is that the installation varies, depending on the distribution.