How is Gmail's bulk sender threshold calculated?

Starting February 2024, Google began to enforce stricter requirements for senders that send more than 5,000 emails to Gmail addresses.

You can find more details about this change in our dedicated post, but you might be wondering how the threshold is calculated exactly.

Google published some FAQs that explain that.

1) Personal Gmail accounts only

First, the 5,000 24-hour threshold only refers to personal Gmail accounts. This means that only emails sent to @gmail.com or @googlemail.com addresses are counted.

Therefore, company addresses hosted by Google Workspace on custom domains are not taken into consideration for this threshold.

Note that even if you send from Google Workspace accounts to personal Gmail accounts you’re not exempted: these emails are considered external.

2) Subdomains sum up

Google uses what they call a “primary domain” to count emails.

For example, if your domain is dmarcwise.io, all emails sent from addresses on this domain are counted. If you also send emails from newsletter.dmarcwise.io, these are also counted as part of the dmarcwise.io calculation.

Google isn’t specific about how they know what a “primary domain” is supposed to be, but we can assume they use the concept of organizational domain, introduced by the DMARC specification.

In that context, the organizational domain is the first registrable domain in the hierarchy. In the example above, the io domain is not registrable since it’s a Top Level Domain (TLD), while dmarcwise.io is.

To obtain the organizational domain we use a list of all the publicly known TLDs called Public Suffix List (PSL) and maintained by Mozilla. For example, io is part of this list and therefore all subdomains of io are to be considered organizational domains.

Most likely, Google is using the PSL to determine the “primary domain” and therefore group domains for the purpose of the 5,000 limit calculation.

3) Bulk senders are permanent

Google also specifies that if a sender is classified as a bulk sender, it will remain so forever, even if the threshold is reached only once.

The bulk sender status does not have an expiration date.

Unfortunately, there’s no way to know if Google has classified a sender as a bulk sender.

The best solution is therefore to ensure that your domains have full DMARC compliance on both SPF and DKIM, even if you are far from the threshold.

At DMARCwise, we can help with that. Feel free to start a free test below or learn more about our services.