By KYN AI Advisory Team — AI implementation specialists, Singapore
An outbound agent must treat out-of-office replies, bounces and unsubscribes as three different events with three different actions. An out-of-office pauses the sequence and resumes it on the return date. A hard bounce removes the address for good. An unsubscribe stops every channel to that contact, in the same run. Most deliverability damage comes from agents that treat all three as "a reply" and keep sending.
This checklist covers what the agent reads, what it does, and what it logs. It assumes a person approves new outbound messages. See is it safe to let an AI agent send emails to customers for that gate.
Why do these three replies matter more than real replies?
A real reply is a sales event. These three are hygiene events. Get them wrong and the cost is quiet: your domain reputation drops, mail lands in spam, and real replies stop arriving.
Mailbox providers measure this. Google's email sender guidelines ask senders to keep the spam rate in Postmaster Tools below 0.10% and to avoid ever reaching 0.30%. An agent that mails an unsubscribed person a third time is the fastest way to add a spam complaint. An agent that keeps mailing a dead address adds bounces that signal a poor list.
The same guidelines say marketing and subscribed messages must support one-click unsubscribe, and that senders above 5,000 messages a day must meet that rule. Small teams sit far below that volume. The practice is still the right default.
What are the six classes of automatic reply?
Have the agent label every inbound message into one class before it does anything else.
| Class | Typical signal | Action | |---|---|---| | Out-of-office | "I am away until 3 November" | Pause, resume after return date | | Hard bounce | Permanent failure, mailbox does not exist | Suppress the address | | Soft bounce | Mailbox full, server busy | Retry later, cap the attempts | | Unsubscribe | "Remove me", "stop", unsubscribe link used | Suppress in all channels, confirm | | Wrong person | "I left the company", "not my area" | Stop, ask for the right contact | | Real reply | Anything else | Send to the reply desk |
The labels are the easy part. The action rules are where agents fail.
How should an agent handle out-of-office replies?
Pause, do not drop. An out-of-office is not a no.
- Extract the return date if one is stated. Store it as a date, not as text.
- Pause the sequence for that contact. Resume on the first working day after the return date.
- If no date is stated, wait a fixed number of days you choose, such as seven, and send once more.
- If the reply names a colleague as cover, record the name. Do not mail the colleague automatically. A person decides whether the cover is a new contact.
- If the reply says the person has left, reclassify as wrong person.
Two failure modes to test. First, auto-replies come in many languages. An agent that only recognises English will label a Bahasa Indonesia or Chinese out-of-office as a real reply. Second, some auto-replies include a "reply to this message" instruction. The agent must not treat those as an invitation to answer.
How should an agent handle bounces?
Split hard from soft. The mail server tells you which in the delivery status code and message.
- Hard bounce. The address does not exist or the domain rejects all mail. Suppress it on the first occurrence. Never retry.
- Soft bounce. The mailbox is full or the server is temporarily unavailable. Retry up to two or three times across several days. If it still fails, treat it as hard.
- Block bounce. The receiving server rejects your message because of reputation or content, not the address. Stop sending to that domain and alert a person. This is a signal about you, not about the contact.
Log each bounce with the code, the time and the action taken. A rising bounce share on one batch usually points to the data source. See how to test a data vendor on 100 records for a way to measure that before you send.
How should an agent handle unsubscribes?
Stop everything, immediately, in every channel. This is the one class where the cost of a mistake is legal as well as reputational.
In Singapore, the Spam Control Act 2007 requires an unsubscribe facility on unsolicited commercial email. The PDPC's Do Not Call Registry guidance covers marketing messages to Singapore numbers. Hong Kong, Indonesia and Malaysia each have their own rules, so check the recipient's country.
Build the rule into the agent, not into a reminder:
- The suppression list is checked before every send, by every agent that sends.
- An unsubscribe on email also suppresses the same person on WhatsApp, SMS and calls.
- Suppression is by person and by company domain if the contact asks for the whole company to be removed.
- The agent sends at most one confirmation message, and none if the person used a link.
- Free-text opt-outs count. "Please stop emailing me" and "tolong hapus saya dari daftar" are unsubscribes. So are angry replies that contain the request.
Never reverse a suppression automatically. Only a person can, and only on a written request from the contact.
What should be logged for each event?
Every event gets one row: contact, class, source message, action, actor and time. The actor is the agent's own restricted account. A person reviewing the log should be able to answer "why did we stop mailing this contact?" in one query.
Review three numbers weekly:
- Bounce share per batch.
- Unsubscribe share per batch.
- Number of messages sent to a contact after an unsubscribe. The target is zero.
That last number is the test of the whole design. If it is not zero, the suppression check is not running before the send.
Where KYN fits
KYN builds outbound and reply-handling agents inside the client's own cloud account. For an insurance brokerage, the reply desk sorts each reply at about S$0.01 per reply, and outreach carries one checkable first line at about S$0.02 per email. Suppression is checked before every send, every action is logged with the actor, and outbound messages wait for a named person.
Before any build, KYN spends the first 14 days reviewing your mailbox setup and suppression lists, and interviewing the people who read replies. The agent itself ships in under 90 days. See sales systems and security.
Frequently asked questions
Should an agent reply to an out-of-office message?
No. Read it, extract the return date and pause the contact. Replying to an automatic message adds noise and can start a loop between two automated systems.
How many soft bounces before an address is suppressed?
Two or three retries across several days is a common rule. Choose a number, write it into the agent as a setting, and treat the address as a hard bounce once the cap is reached.
Is a reply that says "not interested" an unsubscribe?
Not by itself. "Not now" and "not interested" close the sequence for that deal. An unsubscribe is a request to stop all marketing contact. When the wording is unclear, the safe rule is to stop the sequence and send the message to a person.
Checked 30 October 2026.
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