SAME threadId
Inbound message A
action_required = 1
sent_mail_id = -1
time
Message B arrives
same threadId
ingested by the cron job
stamps the previous newest row
A.sent_mail_id = B.email_id
A.track_reply_email = B.email_id
A counts as Replied
leaves Pending Reply
sent_mails row
holds the response