Out-of-office detection

An OOO auto-responder and a genuine human reply are structurally identical inbound emails. Without explicit OOO detection, the system treats every Auto-Submitted: auto-replied as a real engagement signal — permanently pausing sequences, creating rep notifications, and potentially marking the contact as 'replied' when they are simply on vacation. The inverse failure is equally bad: some implementations silently discard all inbound emails to avoid OOO noise, missing genuine replies in the process. iso-25010:2011 reliability.fault-tolerance requires that the system handle this expected abnormal input class explicitly, not by accident.

Check IETF-standard headers before routing an inbound email to reply handling. The Auto-Submitted header is the authoritative signal; subject/body patterns catch non-compliant mail clients.

function isOutOfOffice(headers: Record<string, string>, subject: string, body: string): boolean {
  if (headers['auto-submitted'] && headers['auto-submitted'] !== 'no') return true
  if (headers['x-autoreply']) return true
  const oooPatterns = [/out of office/i, /on vacation/i, /automatic reply/i, /auto-reply/i, /away from/i]
  return oooPatterns.some(p => p.test(subject) || p.test(body.slice(0, 500)))
}

async function handleInboundEmail(email: InboundEmail) {
  if (isOutOfOffice(email.headers, email.subject, email.body)) {
    // Temporarily defer — do NOT mark as replied or notify reps
    const returnDate = extractReturnDate(email.body) ?? addDays(new Date(), 7)
    await deferEnrollmentUntil(email.contactId, returnDate)
    return
  }
  await handleReply(email)
}

Check at least two signal types — Auto-Submitted header plus at least one subject/body pattern — to handle both compliant and non-compliant mail servers.