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.