Ask Al: Help, we're getting URL blocked at Gmail!

Sree writes: Help! Our newsletter business is receiving the Gmail "unusual rate of unsolicited mail mentioning your URL" error message. Specifically: "421 4.7.28 Gmail has detected an unusual rate of unsolicited mail containing one of your URL domains. To protect our users from spam, mail with the URL has been temporarily rate limited. "

"This seems to go away if we send really slowly, but that is far from optimal, as we’re not able to send to our entire subscriber database. What could we be doing wrong? How do we fix this?"

This can be a tricky one to figure out because it’s hard to know exactly which URL or domain in your content is the problematic one. Or it could be more than one. And because you can get small amounts of mail through, testing is difficult. You can’t just test each URL in an individual email message and see which ones get rejected. So you’ll have to do a bit of troubleshooting a bit blindly, without the help of knowing exactly what is to blame.

In your shoes, here’s what I would do.
  1. First, make ABSOLUTELY SURE that your mails fully comply with the new Gmail sender requirements, and confirm that with a tool like Steve Atkins’ “” Even I have been guilty of assuming that certain messages are fully compliant, only to come back later and find that I missed the bit about how DKIM has to include the list-unsub headers in its signature coverage. My theory here is that perhaps any of these new Gmail errors might be quicker to kick in if there is any other header/compliance issue in play.
  2. Make sure you’re signed up for Google Postmaster Tools, and look at domain rep in particular, and complaint rates. My theory here is that if the affected domain in question is your own domain, maybe you’ll see that bad reputation reflected in the GPT dashboard. If the impacted domain is yours.
  3. If you’re using a public or shared short link URL tool (think Bitly), stop immediately! Shared domains are bad news and the public shared domains with link shorteners can be the worst of the worst. If you want to use a tracking domain, make sure it’s your own domain, and not shared with anyone else.
  4. How shared is your platform’s link or click tracking domain? Does the platform have multiple clients using that shared click tracking domain? If you’re the platform, and you’ve got multiple clients sending significant volumes of emails, or various clients where you’re concerned about their sending practices, segment those clients by utilizing a different click tracking domain or subdomain for each. Bad senders can bring down the reputation of shared domains; don’t share those needles.
  5. Look at where you’re linking to. Are any of those link domains or destination domains listed on Spamhaus DBL, SURBL or the Google Safe Browsing blocklist? If so, that’s a lead as to which domain could be causing the issue. It’s not guaranteed to correlate, but I find it suggestive.
  6. And finally, reach out to Google for assistance. They’ve hinted that they’re improving how they handle requests for reconsideration and remediation, and I think your chances of getting somebody’s attention over there are better now than in years past. I don’t know for sure that they’ll respond (in years past, they tended not to), but yes, sometimes, for some senders, things tend to clear up after submitting a ticket and sample headers to Google.
I would caution that if there is third party list data in play (not true/direct/explicit opt-ins) or if there’s affiliate marketing involved, it’s likely to be nearly impossible to solve this issue without the bad data going away and the cessation of any sort of connection to affiliate marketing mail.

Bonus: I'm also going to add, "Don't do anything weird," and by that I mean, don't implement anything in your email that might be interpreted as intending to look like part of Gmail's user interface. I ran into a scenario in the past where buttons or checkmarks or certain types of glyphs in the friendly from would cause intermittent blocking because Google perceived it as deceptive -- as an attempt to mimic the Gmail user interface. If there's anything that could be perceived like this in the body (an extra "report spam" link, "this is not spam because" messaging, anything like that), I'd be concerned that you could be triggering some sort of rare filter meant to catch up specific spammy references. Avoid.

What about you, dear readers out in Deliverability-land? What additional steps would you suggest that Sree take here? Have I missed anything? Let me know in comments below.

And for more information on the new/different types of Gmail domain bounces (URL/DKIM/SPF/etc.), click here.


  1. I've heard that ".us" URLs are sometimes marked as more likely to be spam, but that's often what's available when I want to purchase a domain. What do you recommend?


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