get_email_attachment
Fetch a single email attachment's bytes as base64. message_id is the email's id; attachment_id is an attachments[].id from get_email on the same mailbox (pass the same provider/account). Returns {filename, content_type, size, content_b64}. Use it to pull a contract or invoice PDF from an email, then pass content_b64 to create_contract's or create_bill's pdf_base64. Needs email access plus Contracts or Bills access.
Parameters
- message_id (string, required)
- attachment_id (string, required)
- provider (string)
- account (string)