It should be possible to automate proton email sending via iOS shortcuts app in the same way as it works for the Apple Mail app.

Example workflow:
1. Select Files — lets the user pick one or more files.
2. Send Email — prefilled like:
• Body text: “Hello, here’re my attachments:” and then an embedded File token (the file(s) selected above).
• Fields in the action header: with Subject and to Recipients (both are parameter “chips”).
• Extra fields shown:
• From: (optional)
• Cc: (email addresses)
• Bcc: (email addresses)
• A toggle: Show Compose Sheet (checked), meaning it will open the composer UI instead of silently sending.

⸻

Feature requirements:

1) Shortcuts actions (must-have)

Action: “Send Email (via )”
• Inputs
• To (list of email addresses or contacts)
• Subject (text)
• Body (text; supports inserting variables/tokens from previous steps)
• Attachments (0..n files; accepts Shortcuts “File” type and multiple selection)
• Cc (list)
• Bcc (list)
• From Account (optional; select from configured accounts/aliases)
• Show Compose Sheet (boolean; default true to match screenshot)
• Behavior
• If Show Compose Sheet = true: open your app’s composer prefilled; user can edit and hit Send.
• If Show Compose Sheet = false: send silently in the background (or fail with a clear error if iOS disallows in that state).
• Outputs
• Result (success/failure)
• Message ID (if available)
• Error (human-readable + a code for automation handling)

Action: “Compose Email” (optional but nice)
• Always opens composer, returns draft id.

2) Attachment handling
• Accept multiple files from “Select Files” and attach all.
• Preserve file names + MIME types.
• Support common types: PDF, images, video, ZIP, text, Office docs.
• Handle large files:
• configurable limit + clear errors
• optional “upload link instead of attach” mode (if your app supports it)

3) Recipient + address resolution
• Allow recipients from:
• raw emails
• Contacts
• lists passed in from earlier Shortcut steps
• Validate addresses; fail gracefully with which address is invalid.

4) Account / identity selection
• From maps to:
• chosen mailbox (IMAP/SMTP account) or
• alias identity (Reply-To / Sender if supported)
• If not provided: use default account.

5) UX parity with Shortcuts “chips”
• Parameters must appear as editable token fields in Shortcuts (like “Subject”, “Recipients”, and the File token embedded in the body).
• Support variable insertion in body/subject (e.g., file name, date, clipboard text).

6) Reliability + privacy
• Clear permission prompts (Contacts access only if needed).
• No sending until user explicitly allows silent sending (or require compose sheet).
• Don’t retain attachments beyond sending unless user opts in.
• Return deterministic errors so automations can branch (e.g., “NoAccountConfigured”, “Offline”, “AuthExpired”, “AttachmentTooLarge”).

7) Platform implementation notes (so it actually works)
• Implement via App Intents (so actions show up in Shortcuts properly).
• Support running while locked where possible (otherwise explain limitation via error + suggest compose sheet).