Common delivery error codes
A decoder for the error codes you'll see in your message logs.
Written By Catherine Weir
Last updated 5 months ago
If a message fails, the log will show a numeric error code. Here are the most common ones and what they mean.
4452 — Message queue timeout
•The message expired before delivery
•Usually transient; resend if urgent
4720 — Carrier rejected the message
•The recipient's carrier refused the message
•Check if the number is valid; may indicate a deliverability issue with your campaign
4750 — Rate limited
•You're sending faster than your account is allowed
•Slow down or contact support to request a higher rate
4780 — Daily brand cap exceeded
•You've hit your daily message limit for that carrier
•See our article on daily message limits
9902 / 902 — Handset or network block
•The recipient's device or network is blocking your number specifically
•Could be individual block or a broader reputation issue
If you see these repeatedly
Contact support. Persistent errors often indicate a registration or deliverability issue we can fix.
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