The Mailtemi application is compatible with JMAP.
To configure Mailtemi:
Launch the application. It opens its settings and allows you to click on "Add Account"
Choose JMAP
Click on "Manual Setup"
In "SERVER URL" enter the name of your email account's JMAP server (where to find it?)
Fill in your email and its password, then click again on the "Host" field. At this point, the "Next" button at the top right turns blue. Click on it.
The application verifies your access and suggests giving a name to this account as well as a color. You can also set your display name and your signature. Once done, click on "Done" at the top right.
* The application asks for permission to send you notifications, allow it.
Your emails are now displayed using the new JMAP protocol.