Read the full response#
Keep the enhanced status code, surrounding text, timestamp and receiving host. The same short code can appear in different operating circumstances. Look for a pattern by domain or sending host before classifying individual addresses.
Inspect the connection path#
Check provider incident reports, timeouts and transport logs. Compare affected attempts with successful messages sent around the same time. Do not use a guessed cause to relabel an entire domain as invalid.
Retry with a boundary#
Use your sending service’s queue policy for temporary failures. Avoid simultaneous repeated retries from multiple tools. Preserve unresolved verification results as unknown, and escalate recurring transport problems with a small set of representative logs.