Why There Might Be a Spike in Spam Complaints

Email marketing is a powerful tool for reaching your audience, building relationships, and driving engagement. But it comes with its own set of challenges, with the top one being spam complaints.

In this article, we’ll explain what causes spam complaint spikes and how to use Mailmodo’s tools to investigate and resolve these issues.

What is a spam complaint?

A spam complaint occurs when a recipient marks your email as spam. Every time this happens, it sends a signal that your email was unwanted or suspicious, which can damage your email reputation and ultimately, deliverability.

Generally, a complaint rate above 0.3% on a single campaign is considered a red flag. Consistently exceeding that threshold can result in:

• Reduced inbox placement (lower deliverability)

• Domain reputation degradation

• Temporary or permanent sending restrictions from your email service provider

Why there might be a spam complaint spike

Spam complaint spikes usually aren’t random. Here are the most common culprits:

1. Sudden change in sending behavior

If you ramp up email volume too quickly or start sending after a long pause, recipients may not remember who you are, even if they previously subscribed. This lack of recognition often leads to a quick “mark as spam.” Sudden frequency changes can also trigger fatigue and frustration.

2. Sending to a new list

Newly imported or acquired email lists often contain contacts who didn’t explicitly opt in or have never heard from your brand. These users are much more likely to flag your emails as spam — not necessarily because of the content, but because the send itself feels unexpected or intrusive.

3. Poor timing

Even if your list and message are solid, which time you send your email can still backfire. Emails sent on Monday mornings or weekends might hit overwhelmed inboxes. During the holiday season, people receive more emails than usual, and yours might be the one they flag to clean things up.

4. Content changes or “spammy” elements

Subject lines that feel clickbaity, have aggressive calls-to-action, or template changes that look untrustworthy can cause recipients to question your credibility. Adding to the fact, if the content doesn’t align with what the audience needs, they may react negatively, even if your intent was good.

How to investigate and resolve a spam complaint spike using Mailmodo

Once a spike happens, the best course of action is to investigate its cause - quickly and precisely. With Mailmodo’s segmentation and reporting tools, you can quickly connect the dots.

Here’s how you can resolve the spike based on the likely cause:

1. Sending to a new or imported list

If the spike campaign went primarily to newer contacts with no prior opens or clicks, the issue is probably list quality or a lack of proper consent. Segment your contacts based on when they were added to your system.

2. Poor timing or recipient context

Review campaign analytics to compare performance across different send days. If you notice higher complaint rates and lower engagement on specific days, such as Mondays or weekends, timing is likely the culprit. By spotting these patterns, you can adjust your sending calendar to better match when your audience is most receptive.

3. Email content or subject line issues

Take a close look at the content of the campaigns tied to the spike. Audit your subject lines, formatting, and overall clarity to see if anything feels misleading or untrustworthy.

Mailmodo’s bounce report can also help you understand whether mailbox providers flagged your content as spammy. Together, these checks will show you if content changes were the cause.

Conclusion

Email marketing is as much about understanding people as it is about sending messages. Spam complaints are signals that your audience’s expectations weren’t met. They remind us that even the best campaigns can falter if timing, content, or context aren’t aligned with how recipients experience your brand.

With Mailmodo, you can quickly identify the cause of complaint spikes and optimize your campaigns to ensure messages reach the right people at the right time. Sign up for Mailmodo today to gain full control over your email campaigns and keep your messages landing where they belong.