Notes are stored as messages in a dedicated Notes folder/mailbox on the
IMAP or JMAP server, keyed by the RFC 2822 Message-ID header via the
X-SharedInbox-Note-For custom header. This survives folder moves since
Message-IDs are stable. Multiple users sharing one account see the
same notes. A local Drift cache (schema v39, EmailNotes table) is kept
in sync on demand when the email detail screen is opened.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
