If your emails are getting a lot of spam reports, you've probably developed a reputation for one spammer. Email service providers (ESPs) may start filtering yours emails in email foldersreducing yours engagement metric. Additionally, appearing as a spammer can erode the trust your audience has in your brand. This can lead to lost customers, negative word-of-mouth and, ultimately, a decline in your business growth.

But how do you know if you're getting too many reports? Major ESPs like Yahoo and Gmail have established a clear benchmark: the spam complaint rate should not exceed 0.3%, with the ideal metric being 0.1%.

For many companies, it is easy to collect reports:

• Some subscribers may find it more convenient to report your email as spam instead of unsubscribing.
• Others mistakenly mark your emails as spam.
• 78% of consumers report an email as spam simply because it “looks like spam.”

If the spam complaint rate seems alarming, it's in your power to remedy things and keep the good email deliverability. So where do you start? Here are six common mistakes that can cause your emails to be marked as spam.

Related: 5 Simple Fixes for Better Email Delivery

1. You never asked for permission

Sending emails without permission is one of the most dangerous things you can do in your business. People don't appreciate receiving emails they haven't signed up for and are likely to mark them as spam. This can quickly stain you the reputation and damage your deliverability.

To avoid this, get express permission before adding someone to you email list. Use the double opt-in method where subscribers confirm their email addresses so you can be sure they would like to receive emails from you. Respecting your subscribers' preferences helps you build a long-term relationship with them.

2. People cannot unsubscribe

It's a common reason consumers will mark an email as spam: they can't find a way around it. So make it simple for recipients unsubscribe if they no longer wish to receive your emails.

“You don't have to jump through hoops to stop receiving spam from a particular email sender.” has written Neil Kumaran, Google Group Product Manager, Gmail Security & Trust. Additionally, he added that unsubscribing “should take one click.”

In February 2024, Google and Yahoo were created new rules for sending email stating that:

• All emails must have a visible, working unsubscribe link.
• The user should be able to unsubscribe with just one click.
• Senders must remove unsubscribed email addresses from their lists within two days.

While common in the email industry for decades, these guidelines are now hard rules if you're emailing Gmail and Yahoo users.

3. You use deceptive subject lines

Your subject lines are the first impression your emails make on someone's inbox, so it's only natural that you want to make them catchy. But if they are misleading or do not match the content of the email, people will feel cheated and report your email as spam.

To avoid confusing your subscribers, think of subject lines like newspaper headlines. What is the most valuable or compelling element in your email? Record it in the subject and also don't forget to add preliminary text. Often, the preview text—that's the copy that goes right after your subject line—can attract more clicks than the subject line itself.

4. You are sending too many emails

Bombarding your subscribers with too many emails can overwhelm and frustrate them, making them even more likely to hit the “mark as spam” button. Find a balance in your email frequency to keep your audience engaged without being intrusive.

An easy way to determine the number of emails you send is to go back to what you promised your subscribers when they signed up. If they opted in to your weekly newsletter, avoid sending them a flood of additional promotional emails.

5. You send everyone the same email

Sending generic emails to your entire list without considering their preferences or behaviors can lead to disinterest and spam complaints. If your subscribers don't feel like your emails are speaking specifically to them, you'll lose their attention in seconds.

Segmenting your list and creating more personalized experiences for each customer group and prospect is a much better approach. Once you've set up these segments, you can easily continue adding new prospects to your channels and sending them relevant emails.

Related: Inboxes are overloading. How to keep your emails out of spam.

6. Your email design needs an overhaul

It only takes seconds for someone to form one first impression about your email and every element counts. Poorly designed emails with excessive images, no clear calls to action or too much text can look unprofessional and trigger spam filters.

To avoid appearing as an email sender, pay attention to details such as the sending email address, branding, layout, and image-to-text ratio. If you don't like your email templates, chances are your subscribers won't either. Consider revitalizing your design, making sure everything is on brand and making your emails easy to read.

Last tip: remove complainers immediately

I'm always surprised when a company emails me back after I report an email as spam. It's a big no-no, as the only possible outcome is another spam report. So, put a process in place that removes complainers from your mailing list immediately. Stop reaching out to people who let you know your emails bother them and instead focus on those who open and click through your content. So do you achieve better email deliverability and more successful email campaigns.