Gmail Error: 4.7.28 – Unusual Rate of Unsolicited Mail Detected

What does this error mean?

If you see this error when sending emails to Gmail recipients, it means Gmail has temporarily limited emails from your sending IP due to unusual sending behavior:

4.7.28 Gmail has detected an unusual rate of unsolicited mail originating from your IP

This is not a permanent block or blacklist. Gmail uses automated systems to protect its users from spam. When it detects a sudden spike in email volume or patterns that look unusual, it temporarily slows down or defers emails from that IP to prevent potential abuse.

Is my IP blocked?

No. This error indicates a temporary rate limit, not a permanent IP block. The 4.x.x error code means Gmail is deferring emails, not rejecting them.

Once your sending behavior improves, Gmail usually removes the restriction automatically. No manual delisting request is required.

Why did this happen?

This error commonly occurs due to one or more of these reasons:

• A sudden increase in sending volume, especially to Gmail addresses
• Sending from a new or recently warmed IP
• Campaigns sent to inactive or unengaged families
• Automations sending emails too frequently
• Higher-than-normal spam complaints or low engagement
• Email authentication issues (SPF, DKIM, or DMARC misalignment)

Even legitimate senders can trigger this if email volume increases too quickly.

How to fix this issue

1. Reduce sending volume to Gmail

• Temporarily lower the number of emails sent to @gmail.com and @googlemail.com addresses
• Gradually increase volume over time instead of sending large bursts

2. Send only to engaged families

• Focus on parents who have recently opened or interacted with your emails
• Avoid sending to old, inactive, or purchased lists

3. Review automations

• Check for automations that may be sending emails repeatedly or too frequently
• Pause or adjust any campaigns that caused a sudden spike

How long does recovery take?

In most cases, Gmail lifts the rate limit within 24–72 hours once your sending behavior stabilizes. Continued good sending practices help restore normal delivery faster.