"Thanks for your message! We will get back to you soon." Everyone has sent one. Almost nobody has asked whether it helps, and for a customer with an urgent problem it reads as an acknowledgement that nothing is happening.
What an auto-reply is for
Exactly one job: replacing uncertainty with information. A customer who has just messaged does not know whether it arrived, whether anyone will read it, or when. A good auto-reply answers all three. A bad one answers only the first, which they had already assumed.
The difference in practice
Weak: "Thanks for contacting us! Our team will respond shortly."
Strong: "Thanks — we have got your message. Our team is here until 7pm and usually replies within two hours. If this is about an existing order, reply with your order number and it will reach the right person faster."
The second sets an expectation, states a boundary, and asks for something that genuinely speeds resolution. It also gives the customer something to do, which is the difference between waiting and being stuck.
Only promise what you will hit
An auto-reply promising a two-hour response creates a two-hour expectation. Missing it is worse than never having set it. Quote a time you beat comfortably on a bad day, not your average on a good one.
Out-of-hours messages
This is where auto-replies earn their keep, because the alternative is genuine silence. Say when you are back, in plain terms — "Monday morning" beats "the next business day" — and provide a self-service route for anything urgent. If there is a genuine emergency path, give it; if there is not, do not imply one.
Rules that prevent the annoying cases
- Once per conversation, not once per message. Someone sending three messages in a row should not receive three identical replies.
- Never after a human has replied. The most jarring failure there is: a person answers, then the robot thanks them for their message.
- Not in response to "thanks" or "ok". Detect conversation-ending courtesies and stay quiet.
- Suppress during active handling. If an agent has the conversation open, no automation should speak.
- Cool-down. Do not re-send the greeting to someone who messaged an hour ago.
Keep it short
An auto-reply competes with a customer's patience. Three or four lines. Menus of eight options belong in a proper flow, not in a greeting — and a greeting that requires scrolling reads as a wall put up between the customer and a person.
Review the transcripts
Once a month, read twenty conversations that began with an auto-reply. You are looking for two things: customers who repeated themselves because the reply did not acknowledge their actual question, and customers who went quiet immediately after it. Both indicate the automation is losing conversations rather than holding them.