4. 添付検出キーワード

4.1. $hasattachment

4.2. $hasnoattachment

The $hasattachment and $hasnoattachment keywords help clients determine whether a message contains attachments without fetching and parsing the full message structure. They are mutually exclusive, and a message MUST NOT have both set at the same time.

$hasattachment indicates that a message has one or more attachments. $hasnoattachment explicitly indicates that a processed message has no attachments; absence of $hasattachment alone is inconclusive. With JMAP, the "hasAttachment" Email property MUST reflect the same information as these keywords.