RSVP to event from mail/calendar mobile apps when not on the recipient list
I forward my Gmail to Proton which works fine for email but not events. Even when my contacts use my non-Gmail address on an event, on their side the client (Google?) switches the address to my Gmail information. When I open the event in Protonmail on mobile (Android), I'm unable to RSVP. When I click "Open in Proton Calendar" I get a message at the bottom of the screen in Proton Calendar saying I'm not on the invite list, and nothing show up for that day. Yet, from the Protonmail web mail client I can choose to RSVP directly from the email, without having to use Proton Calendar directly.

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Artem commented
It's not the only problem. Say I get an invite from a Gmail user or any other corporate mail address with a body generated by Zoom. I can click RSVP, and it starts adding to my Proton Calendar, but the contents of an event are a huge pile of mess mixed with HTML and random characters.
It's crucial to add a body sanitizer feature, so all this HTML can be converted to plain text with a plain link.