Knowledge base

How to avoid spam complaints

What are spam complaints?

Spam complaints occur when a recipient reports your email as spam. Receiving a large number of spam complaints can be detrimental to your sender reputation. Having a damaged sender reputation may result in your emails being delivered directly to the spam folder and affect your overall email deliverability.

What happens if a recipient reports an email as spam?

If your recipient's email provider supports feedback loops, MailerSend will be notified of this, and the spam complaint will be reported in your MailerSend analytics.

MailerSend will also automatically move recipients who report your emails as spam to your spam complaints suppression list.

How MailerSend handles spam complaints

As per our Terms of Use and Anti-Spam Policy, we reserve the right to suspend your account and investigate if we detect a high percentage of spam complaints. Specifically, a spam complaint rate higher than 0.2% warrants further investigation. If the rate reaches 0.4% or higher, particularly if you are sending high volumes of email, this will be a cause for concern.

If your account is showing an alarmingly high level of spam complaints, it may be suspended. However, if the spam rate is just above the acceptable rate, sending will be paused and the account holder will be contacted.

3 tips to avoid spam complaints

To maintain a healthy sender reputation, you must employ these best practices to avoid spam complaints:

1. Practice legitimate email collection methods 

If you’re sending marketing emails, you should only add consenting recipients to your mailing list.

Keep in mind that consent expires.

Marketing permission from a recipient lasts for up to 2 years. If you have not contacted that recipient within that time frame, you no longer have the right to do so.

2. Use a recognizable sender address

Always use a sender address that matches your domain name. If a recipient doesn’t recognize you as a sender, they’re more likely to mark your email as spam.

3. Protect your webforms from abuse

Spambots (computer programs designed to carry out repetitive tasks) attack your unprotected webforms by submitting multiple email addresses to your form.

In most cases these email addresses are invalid, which will lead to an influx of hard bounces—But in some cases, spambots will submit purchased lists to your webform that might contain real, valid email addresses. When you then email these recipients, you are sure to see a large number of spam complaints in your analytics.

To prevent spambots from successfully submitting email addresses to your signup forms, you can use one (or more) of the following tactics:

  • Enable double opt-in on marketing signup forms

  • Enable reCAPTCHA on your webforms

  • Include a hidden “honeypot” field on your webforms that only spambots will see and fill out (recipients who enter a value into the honeypot field can then be disregarded)

Avoiding spam complaints is just one way to maintain a good sender reputation and improve email deliverability. Check out this article to learn more ways you can improve your overall email deliverability.

Need more info?

Feel free to reach out to A member of our support team will gladly assist you.