Flooding filter (DCL)

The flooding filter, also called DCL (Destination Counter Limitator), is a platform-level security mechanism. It protects both end subscribers and Infobip clients from accidentally sending a large number of messages to the same destination number. By default, DCL applies to outbound SMS and is enabled for every account.

A message rejected by the filter gets the REJECTED_FLOODING_FILTER status, with the EC_DESTINATION_FLOODING or EC_DESTINATION_TXT_FLOODING error code. Unlike API-level throttling, the API request still succeeds: the rejection shows in the delivery report and message logs, not as an HTTP 429. Rejected messages are not charged.

Default thresholds

The following table lists the default thresholds:

Impact on integrations

When building or testing integrations, be aware of the following:

• Sending the same OTP or test message more than 6 times within 60 minutes to the same number triggers DCL.
• Retry logic that resends identical content can silently exhaust the threshold. See Retry safely.
• Rejected messages also count toward the limit. With the default settings, stop sending to that number for 60 minutes to clear it.
• By default, DCL counts messages per destination number on your account, regardless of the sender. DCL is set separately for each sub-account.
• To exclude a test number from DCL, ask your account manager or Support to safelist the number.

Adjust or disable the filter

To adjust or disable the flooding filter, contact your account manager or Support. You can ask for different limits, a different time window, or a rule for a specific country or sender. Keep the filter enabled for most use cases. The default thresholds protect against both accidental loops and fraudulent use of your account.