Email deliverability problem:- Nation Builder (via G-Suite) to Yahoo

meirionwyllt used Ask the Experts™
In a Nation Builder nation, I have a 700-member e-mail recipient list. The majority of these recipients were imported when my nation was set up a couple of months ago. Email to these recipients is solicited because they all pay a monthly/annual fee for membership.

I've sent about a dozen email blast in this time without problem, and I get stats on how many people opened links inside the emails, how many bounces, how many are ad addresses. However a couple of weeks ago, I sent one out and it first reported everything to be OK, with zero bounced, but after about 4 days, the bounced shot up to 117. This was highly irregular because the highest number of bounces before this was about 8. I had a look at the 117 and they are all Yahoo, AOL or Sky addresses, and since AOL and Sky go through Yahoo, we can assume that this is specifically a Yahoo problem. Here's the message that appears in Nation Builder next to each bounce...

4.0.0 Email was deferred due to the following reason(s): [IPs were throttled by recipient server]

I've done two more blasts since this, and the same thing happens. I've checked with a few owners of these email addresses and can confirm that the emails are not being received.

Is there anything I can do to help this situation, either on Nation Builder, on Google G-Suite, or on Yahoo? I've contacted Nation Builder support, but all they suggested was that I send a handful of emails at a time in order to rewarm Yahoo. But this could take a long time, especially since I have to wait 4 days just to see if it worked.

One thing that might be of interest, is that among the 117 bounced, two of them have this bounce message instead...

4.7.0      421 4.7.0 [TSS04] Messages from temporarily deferred due to user complaints -; see

Any help would be appreciated. Thank you.
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
David FavorFractional CTO
Distinguished Expert 2018

You said, "I've sent about a dozen email blast in this time without problem".

Many people operate under the misconception that if email is working today, it will also work tomorrow.

This is incorrect.

Each time you send an email, you must look at STMP return codes, then if you get any sort of spam or thin content message from one Mailbox Provider, you have to stop sending to that Mailbox Provider.

Mailbox Provider == Google, Apple, Oath (owns Yahoo/AOL recipients), etc...

Most likely you didn't have access to your SMTP return codes, so you didn't even know, because...

MailGun is the only service I know about which correctly report 100% of SMTP return code messages.

Fix: Since you have so few people on your list + you have all of them on continuity, best to call them up on the phone + tell them to white list your domain + find all your mail + hit the "This is not SPAM" button in their mail reader.

I also go one step further + tell people, "If you use Oath (owns Yahoo/AOL email addresses) for email, likely you will never correctly receive an email from me. You won't receive messages about payments, billing problems, package tracking messages, password resets. Nothing. If receiving {project name} email is important, please login + change to using a Gmail address."
meirionwylltSenior Desktop Engineer


Thanks for your reply. However I don't have a phone number for the vast majority of these. And telling people to switch email provider isn't an option for me.

Is there nothing I can do improve my domain's reputation?

I've come across the 'Yahoo Complaint Feedback Loop (CFL) Service' - would joining this scheme help this situation at all?
David FavorFractional CTO
Distinguished Expert 2018

There's no easy way to fix this.

You'll have this continual problem with Oath addresses, just like anyone else.

You can setup the Yahoo FBL + you still must change how you send email.

For example, if you just blast email to Oath addresses without checking the SMTP returns, you'll end up in this situation repeatedly.

Whenever you get a single return where you're told by Oath (or any other Mailbox Provider) your message looks spammy (to them) or your content is "to thin" (to them), then you must stop sending the offending message.

For example, your message may work with all non-Oath recipients, so you send to all these.

Then for Oath recipients, you have to recraft your message, then send to one recipient. If the message is accepted with no warnings, then you must still trickle out mail to Oath recipients.

I recently worked with a list where 100K recipients were Oath recipients. After around 6 weeks, I was able to deliver 1 message every 10 minutes with no throttling.

In other words, this is not your problem, it's how Oath handles email delivery.

Everyone sending mail has exactly the same problem. It's just that most mail delivery services like about their deliverability.

The only way you'll really see + understand the problem, so you can fix the problem, is use MailGun + trap 100% of all message state changes via Webhooks.

My guess is most people will be horrified at the SMTP responses coming back.

Keep in mind, every list is only one message away from going to zero deliverability for all Mailbox Providers, which is why all SMTP return messages must be analyzed on a per message basis, to determine if it's acceptable to keep sending a given message to a given Mailbox Provider.

Tip: If you have a login facility for your subscribers, like a WordPress dashboard, you can publish messages about new content in the dashboard.

Tip: Run a support ticket system + tell them up front (if they are an Oath user) they won't get any email about their tickets, then do all ticket work in a Web based system.

This may seem complex + it's just part of the cost of doing email business these days.
meirionwylltSenior Desktop Engineer


Thankfully, there was a very simple solution to this - DNS records. One of the first questions I asked Nation Builder when I noticed the problem was "can you check everything's OK with my DNS", which they didn't respond to, saying instead that I need to rewarm etc. But then I asked again, and someone else picked up the call, and changed something, and now all is well, people are receiving emails from me for the first time in weeks.

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial