Gmail Error: 4.7.28 – Unusual Rate of Unsolicited Mail Detected

What does this error mean?

If you see the error below while 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 may temporarily slow down or defer 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 sending behavior improves, Gmail usually automatically removes the restriction.

• No manual delisting request is required.

Why did this happen?

This error commonly occurs due to one or more of the following 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 contacts

• Workflow or automation 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 contacts

• Focus on users who have recently opened or interacted with your emails

• Avoid sending to old, inactive, or purchased lists

3. Review automations and workflows

• Check for workflows 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 sending behavior stabilizes. Continued good sending practices help restore normal delivery faster.


The 4.7.28 error is a temporary Gmail protection mechanism, not a permanent block. By slowing down email volume, sending to engaged users, and following Gmail’s bulk sender best practices, email delivery will recover naturally.