Bounce error fix
Gmail is slowing your email down because of spam complaints or a sudden jump in volume. Here is how to recover.
421-4.7.28 Gmail has detected an unusual rate of unsolicited mail originating from your IP address or domain. To protect our users from spam, mail sent from your IP address has been temporarily rate limited.
It’s a temporary block: Gmail is slowing you down because too many people marked your email as spam, or your volume jumped suddenly. If it turns into a permanent block, you’ll see 550 5.7.1 instead.
Slow down now. Pause or cut sending from the affected domain or inboxes. Pushing on makes the block longer.
Check your spam rate. Google Postmaster Tools shows the rate Gmail sees. Keep it under 0.3%, ideally under 0.1%.
Clean your list. Remove addresses that never open or reply, and verify new lists before you send.
Make sure SPF, DKIM and DMARC pass. Unauthenticated mail gets far less patience. Run the full domain scan.
Ramp back up slowly. Spread volume across more inboxes and domains. The cold email calculator shows how many you need.
Plan your sending
Work out how many inboxes and domains you need to send your volume safely.
