@robing It would be great if the DeskApp is made available as a Universal App so that it runs natively (and without Rosetta 2) on the new hardware with the Apple M1 SoC. Also, the adaptation of the app logo to the look & feel of macOS Big Sur would be great.
If the file format is something your computer should be able to open, but it’s not opening correctly, its file format may be associated with the wrong program. … Instead of trying to open the attachment directly from your e-mail client, save the attachment to your computer (e.g., save it to your desktop).
In the end its security features of Mailstore that are interfering here (and usually for the right reasons). Mailstore seemingly sets a “content security policy” (csp for short) that prevents that it gets embedded from other domains (like you have webapp at https://kopano.domain.com/webapp and mailstore at https://mailstore.domain.com, using a different port for both also makes it a different domain for the browser).
DeskApp is configured to ignore this by default, that is also why there is a WhatsApp plugin only for DeskApp and not for WebApp itself.
What are your options? You could modify the webserver serving Mailstore to override the csp to allow embedding from your WebApp domain. We have been doing something similar when it came to the integration of Mattermost into Kopano WebApp.
However, WebMeetings remains in a separate window and not as a tab in DeskApp as seen on the website:
I think the screenshot on the website is just not 100% intuitive. You can see that the mail context is still highlighted so the “tab” would show mails and not WebMeetings. In fact it looks like the WebApp window is just placed and resized so that it looks neatly organised next to the mail view.