"transient error (421): 4.7.0" when forwarding emails to Gmail

Cloudflare listed in Spamhaus so it fails for iCloud as well

Sorry, not trying to imply Gmailify uses Cloudflare… (And so far Gmailify has been working like a charm!)

I was saying spammers are sending direct to Cloudflare. Even now (5 days after removing the Cloudflare SPF and MX records) I am seeing spam arriving in Cloudflare for my domain (And still failing delivery. But now with good reason as it’s failing SPF)

Ah, thanks for clarifying! Sorry for misreading that!

In case Cloudflare is watching this thread, I am still missing a bunch of emails due to the rate limiting:

Unknown error: transient error (421): 4.7.28 Gmail has detected an unusual rate of unsolicited mail originating4.7.28 from your DKIM domain [cloudflare-email.net 36]. To protect our4.7.28 users from spam, mail sent from your domain has been temporarily4.7.28 rate limited. For more information, go to4.7.28


Please don’t needlessly tag people. There is an incident status that you can track for updates. You can see from that status that the incident is considered ongoing and there is nothing new reported.

holly was answering in one of the hundret ongoing mail problem threads. just tagged to help pointing eyes on the most active of them.

the incident says “email deliverability levels are returning to normal” which is not true.

It says are returning not have returned which indicates delivery rates are still abnormal. Based on the continuing reports in this and other topics, that sounds accurate.

Participation in a topic is not an open invitation to be tagged. Cloudflare staff are aware of this topic and will reply here should they have anything pertinent to add. They dont need to be summoned.

Guys, should we expect the deliverability problem fix or abandon Cloudflare → Gmail routing? I’m still experiencing huge delays and it’s intolerable.
Looking forward to returning back to Forwardemail (which I left someday because of similar problems, by the way :frowning: )

I have implemented Email Workers and getting all emails for over a week, no issues.

Implement it as well with Outlook backup, outlook forwarding and Gmailify (from Google) and you will not even notice any delivery issues.

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So you have all your mails delivered to your gmx.de mailbox, right?
If Gmail fails, you have a backup delivery address?

No, I am using solution 3 from my post, which is referred here earlier.

If fail Outlook

outlook forwarding anything to Gmail if they land in Inbox

Anything that land in Spam are taken to Gmail by Google Gmailfy.

Single items not passed, but it’s Russian spam.

Like this?

export default {
  async email(message, env, ctx) {
    await message.forward("[email protected]").catch((err) => {
      return message.forward("[email protected]");

Outlook forwards to Gmail?

And do you turn off Cloudflare’s Email routing in this case?

Yes, that’s it.

No, you not turning Cloudflare forwarding. You changing route from email to worker.

And add outlook from email settings at Gmail as well.

On one hand my worker executes mail forwarding, on another it doesn’t seem to resend the “stuck” mail (from “problematic” domains) to my alternative e-mail. I’m also confused by statistics here:

And the worker with the code as we discussed returns:
SPF status


DMARC status


DKIM status


Rejected reason:

Worker call resulted in an error: Worker call failed for 3 times, aborting…

On one hand the email can be indeed spam if it contains DMARC and DKIM status none. Any more information about from which email it originates?

Have you got your both email added to Routes on Cloudflare and both are verified? Email will not work in worker if its not verified in routes.

Yes, sure, my receiving mail is added to the verified list. I’ve been using Cloudflare’s Email Routing for over 2 years until 4.7.0 appeared recently. The senders are from different domains, all official company e-mails. Well, I finally left this worker’s tinkering and switched to the Enhanced Forwardemail.net plan. Now it forwards e-mails instantly. It’s a shame for Cloudflare to have such issues.