How to interpret Gmail’s “rate limit exceeded” message?

Gmail rate limit errors indicate you've exceeded acceptable sending thresholds for your account or domain.

Common rate limit messages:

• 421 4.7.0: Temporary rate limiting, try again later
• 421 4.7.28: IP reputation too low, rate limited
• 550 5.7.1: Blocked due to content or reputation

What triggers rate limits:

• Sending too many emails too quickly
• Exceeding per-account daily limits
• Poor engagement history affecting reputation
• Recipient complaints or spam folder placement

Immediate response:

• Reduce sending volume immediately
• Add delays between sends
• Pause campaigns if limits persist
• Don't try to push through limits

Investigation steps:

• Check Gmail Postmaster Tools for reputation status
• Review recent sending patterns for anomalies
• Check for authentication failures
• Assess engagement metrics for recent campaigns

Recovery:

• Lower volume significantly for several days
• Focus on engaged recipients only
• Gradual return to normal once limits clear
• Rate limits are warnings. Ignoring them leads to harder blocks.