List attachments

List every attachment on one received email, in the order it was stored, each with a download link. A link lasts at most one hour; expires_at is the exact time it stops working and can be sooner. The link saves the file under its original filename. For an email whose virus verdict is FAIL, no files were stored, so download_url and expires_at are null. Returns the same 403 email_above_quota and 404 as the email itself. Not paginated. Requires the read:inbound scope.