Automated reply filtering

Automated reply filtering is a gate before a message reaches the normal sales response queue. Read each message as a mail system would: inspect headers first, then use the message type and context to decide whether a human needs to respond. Treat every inbound reply as possible automation before treating it as engagement. A new message can itself be an automatic reply from another system.¹ Senders can indicate automation in other ways.²

Run the filter

Start with machine-readable signals, then check the message context if the headers leave room for doubt. Stop the normal reply path as soon as a clear automation signal appears.

Check the Auto-Submitted header

Start with the header that exists for this purpose. Check whether Auto-Submitted is present and what value it carries.

RFC 3834 defines the Auto-Submitted header.³ It is the official standard for indicating that a message is an autoreply.⁴ If the header is present with any value other than no, suppress the sales reply.⁵

An out-of-office message can carry Auto-Submitted: auto-generated.⁶ Treat it as an automated message and move it out of the normal human response queue. A value of no does not settle every case, so continue to the next check.

Check the suppression header

If the message has X-Auto-Response-Suppress, check whether it contains a suppression value.

Do not send a reply when X-Auto-Response-Suppress contains DR, AutoReply, or All.⁷ Record the value that triggered the decision so someone reviewing the message can see why the filter acted.

Read the message type

Headers settle some cases. The message itself can identify the kind of automated response.

An autoresponse is a program-generated reply to received mail sent to the bounce address.⁸ Common examples include vacation messages, challenge-response spam-filtering challenges, list-server replies, and feedback reports.⁹ Label the message by type when that distinction affects follow-up or reporting.

If the header checks and message type do not settle the case, send the message to a review path. Reliably detecting automatically generated emails is not always easy.¹⁰ A review path keeps an uncertain message from triggering an automatic follow-up while preserving it for inspection.

Decide where the message goes

The filter determines what happens next, so give each result a clear disposition and keep the reason with the message.

For a confirmed automatic reply, suppress the outbound response and remove the message from the normal sales response queue. An autoreply system should not send replies to automatically generated emails.¹¹ Sending a reply to one can produce a useless delivery failure or an infinite email loop.¹²

Automatic reply detection prevents embarrassing follow-ups to prospects who are already talking to the sender.¹³

For an uncertain message, leave the outbound action paused and send it for review. The reviewer should be able to see the headers, the message type, and the rule that failed to produce a clear answer. Once the reviewer decides, apply the same disposition to similar messages.

Protect your own automation

Your outbound automation can create the same loop that the inbound filter is trying to prevent. Label automated messages clearly so other systems can identify them when they arrive.

Automated responses should include a header like Auto-Submitted: auto-replied.¹⁴ Use that label on every automated response your systems send, then apply the inbound header rule to messages that return.

Keep the suppression action separate from the reporting action. A message can be removed from the sales response queue while remaining available for audit and measurement.

What not to do

These mistakes can turn a harmless acknowledgment into a follow-up or reporting problem.

• Do not let two automated senders answer each other. Two misbehaving bots can endlessly exchange auto-replies and create a mail loop.¹⁵
• Do not assume a sequence has stopped because an automated message arrived. A sequence treats a recipient reply as a stop signal and excludes out-of-office auto-replies from that stop behavior.¹⁶
• Keep auto-replies, out-of-office messages, and role-based inboxes out of the same reply totals. Classify them separately so they do not inflate reply and positive reply rates.¹⁷
• Do not assume Precedence: bulk or Auto-Submitted prevents every bounce or loop. Some inboxes may still bounce or loop the message.¹⁸

Close the loop

Keep the original headers with the message, along with the classification that caused the routing decision.