Notification Shows as 'Sent' but the Customer Says They Didn't Get It

Sometimes the admin screen clearly shows a booking confirmation notification as "sent", yet the customer says they never received anything. This isn't a system fault — it comes down to what "sent" actually means.

Example: Say a hair salon sends a booking confirmation via Kakao AlimTalk, and the admin screen shows it as "sent". Around their appointment time, the customer calls the salon directly saying they never got a reminder. Checking the send history confirms the system successfully handed the message off to Kakao, which is why it's recorded as "sent". The actual cause turns out to be that the customer had business-channel notifications turned off in their own Kakao Talk settings — something neither Biseo nor the Kakao API can see or report back on.

1. What "sent" actually means: The notification status field only has six possible values — queued, sent, failed, skipped, trial_restricted, and quota_exceeded — and there is no "delivered" status. "Sent" simply means the message was successfully handed off to the relevant provider's API (Kakao, Twilio for SMS, or Resend for email). Whether it actually reached the customer's phone or inbox is something these providers don't report back, so Biseo has no way to confirm it.

2. Common causes when a customer says they didn't receive it despite "sent":

   • An outdated or incorrect phone number or email address on file
   • The customer's own Kakao Talk settings blocking business channel messages
   • Email landing in a spam folder
   • Simple carrier delay

3. Why there are multiple channels: For how the automatic channel fallback works when one channel fails, see "How does notification channel priority work?". For the AlimTalk templates and sending conditions themselves, see "Kakao AlimTalk templates and sending conditions".

A "sent" status means the system did its part — it doesn't guarantee the customer actually saw the message.