SMTP code 454 4.7.0
What the knowledge base's own tables say about this code, and which articles say it — a description of the reply, never a placement prediction.
This line comes from a knowledge base article on Gmail, not on the standard.
- Message
- "Too many login attempts" / "Cannot authenticate due to a temporary system problem"
- Meaning and fix
- Throttling of client authentication; retry later
From Gmail SMTP Errors and Troubleshooting · Temporary failures (4xx)