Spam rate in email marketing

The spam rate is one of the most important and underrated metrics in email marketing.

Since it doesn’t get the attention it deserves, it is often checked too late.

It is usually reviewed only after problems have already appeared and deliverability drops.

As spam complaints increase, your domain reputation suffers.

Deliverability drops, performance falls, sales decrease, and your ROI takes a hit.

Let’s properly break down this important metric.

What is the spam rate in email marketing?

The spam rate is the percentage of recipients who mark an email as spam or junk.

It doesn’t refer to the emails that Gmail, Outlook, Yahoo!, or other servers classify as spam.

It refers to emails that the actual recipients mark as spam.

Therefore, this metric measures how many people tell their email provider that they never want to receive your messages again.

It is, therefore, a key signal for email providers—the servers receiving the emails.

Gmail, Outlook, and other providers use it to decide what to do with your future campaigns.

Whether to place them in the inbox or send them straight to the spam folder.

How to calculate the spam rate

The formula is very simple:

Spam rate = (spam complaints / sent emails) x 100

For example, if you send 10,000 emails.

If 10 people mark them as spam, your rate would be 0.1%.

It seems like a small, insignificant figure compared to the volume sent, but it is not.

It is a heavily weighted metric.

Most email servers like Gmail and Outlook limit the spam rate to 0.3%, and if exceeded, they may:

• Reduce the amount of emails successfully delivered, triggering bounces for the rest.
• Route your emails directly to the spam folder.
• Completely block your outgoing emails.

In email marketing, this tiny figure can completely change the outcome of a campaign.

And not just that campaign, but any future campaigns you send.

That is why you must closely monitor your spam complaint rate.

This is a metric you can find in your Mailrelay statistics.

Why the spam rate severely impacts deliverability and ROI

The spam complaint rate affects your results in three main ways.

First is visibility.

If your emails receive too many spam complaints, they are considered unwanted—for obvious reasons.

As a result, every campaign you send has a lower chance of reaching the inbox.

Second is the cost.

Sending to contacts who don’t want your messages wastes time, resources, and sending volume.

And, of course, it yields very poor results.

Third is conversion.

If emails land in the spam folder, they are highly unlikely to be seen.

If they aren’t seen, they aren’t opened.

Without opens, there are no clicks to your website, meaning sales and conversions simply won’t happen.

That is why increasing email volume will not improve your results if that increase generates more spam complaints.

Important!

Spam complaints gradually damage your domain reputation. They essentially accumulate over time, which can lead to two scenarios:

• You receive a high number of complaints from a single campaign, causing an immediate hit to your sender domain.
• Or you get a few complaints across all your campaigns, slowly chipping away at your sender domain’s effectiveness.

In either case, your results will be affected.

Which spam rate values should you worry about

Although it’s hard to provide a specific figure that applies to all situations, we’ll try to break it down.

Above all, let’s make it clear that your spam complaint rate should be kept as close to 0 as possible.

While a common rule of thumb recommends staying under 0.1% for spam complaints, the reality is that the lower, the better.

You can use the following figures as a general benchmark:

• Under 0.03% spam complaints. This is ideal, and it’s what we at Mailrelay recommend to ensure excellent deliverability.
• 0.1% spam complaints. This indicates an underlying issue that you need to fix as soon as possible.
• 0.3% spam complaints. This almost certainly means you will start noticing penalties applied to your sender domain.

If you notice your numbers rising, take action immediately.

Don’t keep sending email campaigns as if nothing happened.

Main causes of a high spam rate

· Poor contact acquisition

Review everything from the start, beginning with how you capture contacts for your email list.

If your contacts are unsure about what you will send them, why, or how often, complaints will likely surface quickly.

Even if you include an unsubscribe link.

Many times, contacts express their frustration simply by marking your emails as spam.

· A very old list

If you haven’t emailed your list in a long time—for instance, more than three months—it’s highly likely it is outdated or your contacts have forgotten about you.

These types of lists, even if they consist of your own customers, typically cause a lot of problems and yield few results.

Do not leave your list abandoned without sending campaigns for long periods.

· Poor sender domain authentication

Before sending, you need to configure:

• SPF
• DKIM
• DMARC

Without these configurations, your email campaigns might be flagged as spam, damaging your sender reputation.

How to reduce your spam rate without stopping your email growth

The best way to lower your spam rate is not by sending fewer emails.

Rather, it’s ensuring your email acquisition process is as careful and transparent as possible.

Clearly explain exactly what subscribers will receive and how often.

Ideally, use double opt-in on your forms.

Also, monitor whether contacts go months without engaging with your emails. If so, it might make sense to try a re-engagement campaign, or remove them from the list if that fails.

On the other hand, always ensure your unsubscribe process is incredibly easy.

If the unsubscribe link isn’t visible enough, many people will simply opt to mark the email as spam.

Remember, a spam complaint causes much more damage than a voluntary unsubscribe.

Frequently asked questions about the spam rate

What is a good spam rate?

A good spam rate is one that is as close to zero as possible.

If zero isn’t possible, try to keep it as close to the figures we discussed above as you can.

The Mailrelay dashboard will alert you if your complaints rise above 0.03%.

If this happens, investigate what might be going on.

If you aren’t entirely sure, you can contact our support team through the Help menu in your account.

Is the spam rate the same as the spam complaint rate?

Yes, in most contexts they are used interchangeably.

Does the spam rate affect deliverability?

Absolutely. It’s one of the factors that affects it the most—negatively, of course.

As spam complaints accumulate, the chances of your sender domain being penalized increase.

Can I have a good open rate and a high spam rate at the same time?

Yes.

Yes, and it is not as rare as it seems.

This can happen if you mix several lists obtained in different ways, or even if everything is correct but your unsubscribe link isn’t clearly visible.

What should I do if my spam rate spikes suddenly?

In these cases, pause your email campaigns and analyze the root causes.

If you have any doubts, reach out to support for help.

Above all, don’t continue sending campaigns, as the situation can quickly get worse.

Does the spam rate impact email marketing ROI?

Yes.

If your emails are no longer seen, every campaign becomes less profitable.

That is why a high spam rate doesn’t just impact deliverability.

It directly impacts the results and sales of your campaigns.