Custom mail attributes com_apple_mail_attachmentNames com_apple_mail_attachmentTypes com_apple_mail_attachmentSpecificTypes com_apple_mail_attachmentKinds com_apple_mail_dateReceived com_apple_mail_dateLastViewed com_apple_mail_read com_apple_mail_flagColor com_apple_mail_flagged com_apple_mail_repliedTo com_apple_mail_priority com_apple_mail_messageID kMDItemEmailConversationID com_apple_mail_attachmentNames com_apple_mail_attachmentTypes com_apple_mail_dateReceived com_apple_mail_dateLastViewed com_apple_mail_read com_apple_mail_flagColor com_apple_mail_flagged com_apple_mail_repliedTo com_apple_mail_priority com_apple_mail_messageID