Do Not Use Money Signs in the Subject

Spam is universally disliked by users, and companies spend billions each year trying to prevent it. Email providers, ISPs, and corporate servers all run complex filtering systems that automatically scan each message before it reaches the inbox. If your email campaign looks too similar to spam, even when your intentions are good, it will be redirected straight into the junk folder. One of the simplest but most common mistakes is the misuse of dollar signs and other “spam trigger” elements.

Why Dollar Signs Can Be a Problem

For years, spammers have relied on dollar signs to attract attention. Subject lines filled with $$$ or messages like “Save $$$ Now” became a symbol of unwanted and fraudulent offers. As a result, most email spam filters treat the dollar sign as a red flag. Using it too often—especially in the subject line—can instantly raise the spam score of your message and lower its chance of reaching the inbox.

Safe usage: Including a price like $19.95 or $9.99 in the body of your email when describing a product.
Unsafe usage: Writing “$$$ Big Savings $$$” or “Only $ Today!” in your subject line.

How Spam Filters Judge Your Emails

Spam filters do not rely on a single rule. Instead, they combine dozens of signals and assign a score to every message. If the score passes a certain threshold, the message goes directly to spam. Some of the most common checks include:

Keyword analysis: Phrases like “FREE MONEY,” “Act Now,” or “100% Guaranteed” are automatically suspicious.
Symbol overuse: Repeated use of $, !!!, or other symbols looks unnatural.
Sender reputation: If your domain or IP has a history of sending mass emails, it may already have a bad reputation score.
Engagement signals: Low open rates and high bounce rates will also push your messages closer to the spam folder.

Understanding these factors helps you design an email that looks trustworthy to both users and filters.

Best Practices to Avoid the Spam Folder

1. Limit Dollar Signs

Use dollar signs only when you truly need to show a price. Keep them inside the body, never in the subject line, and never repeat them multiple times.

2. Avoid Shouting

Subject lines written in ALL CAPS with three exclamation marks look aggressive and unprofessional. Filters treat them as typical spam. Instead, use normal capitalization and let your words provide urgency, for example: “Limited-time offer available until Friday” instead of “BUY NOW!!!”.

3. Use Natural Language

Think about how you would write to a friend or colleague. Emails that read like a conversation are more engaging and less likely to be flagged. Avoid robotic phrases or overused marketing clichés.

4. Balance Text and Images

Emails that are only one big image, or that have too many flashy graphics, often look suspicious. Always include a healthy balance of text and visuals. Make sure the message is understandable even if the images are blocked.

5. Personalize When Possible

Using the recipient’s name or tailoring content based on their preferences not only builds trust but also increases engagement. Higher engagement helps improve your sender reputation, making your future campaigns less likely to be filtered as spam.

6. Test Before Sending

Run your campaign through an email testing tool that simulates spam filters. This allows you to detect risky phrases, broken links, or formatting issues before the campaign reaches thousands of inboxes.

Enhancing Sender Reputation

Your sender reputation is a critical factor in inbox placement. It reflects how ISPs perceive your domain and IP address based on past behaviors. A strong reputation means higher deliverability; a poor one leads to more messages hitting spam.

Consistent sending schedule: Send emails on a regular cadence to avoid spikes that look like spamming.
Clean up bounced emails: Remove hard bounces immediately and retry soft bounces only a few times.
Encourage engagement: Ask subscribers to add your email address to their contacts or whitelist.
Monitor blacklists: Use tools like MXToolbox to check if your IP or domain appears on common blacklists.

Authentication Strategies

Proper authentication tells spam filters that your emails are legitimately from you, not malicious actors. Implement these protocols:

SPF (Sender Policy Framework): Publish SPF records in your DNS to authorize your sending servers.
DKIM (DomainKeys Identified Mail): Sign outgoing messages with a cryptographic signature linked to your domain.
DMARC (Domain-based Message Authentication, Reporting, and Conformance): Define a policy that specifies how receivers should handle emails failing SPF or DKIM.

Setting up SPF, DKIM, and DMARC not only improves deliverability but also protects your brand against spoofing and phishing attempts.

Long-Term Deliverability Insights

Maintaining inbox placement is an ongoing effort. Here are strategies for sustainable deliverability:

Engagement-based segmentation: Regularly segment out inactive subscribers and re-engage them with targeted win-back campaigns.
Content rotation: Vary your email formats and topics to keep engagement high and avoid filter fatigue.
Regular list hygiene: Audit your mailing list quarterly to remove outdated or low-engagement contacts.
Transparent frequency: Communicate your sending frequency at signup so subscribers know what to expect.

These measures ensure your sending practices evolve with changing ISP algorithms and subscriber preferences.

Practical Example: Retail Promotional Blast

A retail brand avoided spam traps during their Black Friday campaign by:

Segmenting customers who purchased in the past year.
Personalizing subject lines with customer names and location-specific deals.
Limiting special characters to one % and no dollar signs in the subject.
Implementing SPF, DKIM, and DMARC records before the campaign.
Monitoring deliverability in real time and pausing if bounce rates spiked above 2%.

As a result, 95% of their emails landed in the inbox, and click-through rates increased by 18% compared to the previous year.

Other Common Spam Triggers to Watch

Overusing the word FREE in subject lines.
Using misleading call-to-action links that do not match the final URL.
Sending attachments with suspicious file types like .exe or .zip.
Sending from a “no-reply@” address instead of a real, monitored inbox.
Failing to include an unsubscribe link or company address.

Protecting Your Brand and Reputation

Getting caught in spam filters does more than hurt one campaign. It damages your brand image and lowers consumer trust. If subscribers expect value but instead see emails that look like spam, they are more likely to unsubscribe or report your messages. Over time, this leads to a poor sender reputation that affects all future campaigns.

Conclusion

In today’s competitive environment, avoiding spam filters is not just a technical detail—it is a core part of successful email marketing. By avoiding excessive dollar signs, limiting aggressive symbols, and writing with clarity and honesty, you give your messages the best chance to reach the inbox. Implement robust authentication, monitor sender reputation, and adopt long-term deliverability strategies to keep your campaigns on target. Focus on value, trust, and authenticity, and your audience will reward you with attention and engagement.