- sendEmail dispatches on account type: IMAP keeps SMTP+APPEND path,
JMAP chains Email/set create + EmailSubmission/set in one API call
- Sent mailbox looked up by role='sent' from local DB so sent mail lands
in the right folder
- JmapClient gains uploadUrl/eventSourceUrl/capabilities from session,
supportsSubmission getter, withSubmission flag on call(), and uploadBlob()
for attachment upload before send
- Mailboxes table gains nullable role column (schema v8); _upsertJmapMailboxes
persists role from JMAP Mailbox/get response
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
