The Dangers of Misleading Subject Lines: “Sale Ends at Midnight” and Other Legal Pitfalls 

Email remains a phenomenally effective marketing channel. The Litmus State of Email 2025 report quotes an average return on investment of 36:1. While many tend to focus on email’s direct contribution to revenue, its value is also measured in terms of customer engagement, brand awareness, and customer loyalty. 

One of the key reasons why email is so effective? It builds a strong foundation of trust between senders and customers—and that trust often starts with the subject line. 

Marketers must tread a fine line here. On the one hand, subject lines need to build expectations around the email’s content, piquing enough interest to persuade recipients to open the message. On the other hand, if subject lines fail to match the content inside, senders will be punished with reduced engagement, opt-outs, and spam complaints.  

Crossing the line into legal implications 

While most subscribers will tolerate some degree of “marketing puffery,” senders that overstep the bounds between fact and fiction will be punished—both by subscribers and sometimes by the law.  

Before we go any further, I should mention that I am not a lawyer, and this blog post should not be considered legal advice—but I’ve provided links to cases if you’d like to continue digging into email marketing true crime. 

• Back in 2006, Jumpstart Technologies settled a $900K claim with the Federal Trade Commission (FTC) over sending disguised and misleading emails to consumers.  
• In 2015, Canada’s Competition Bureau filed a notice alleging deceptive marketing practices by Avis and Budget. This resulted in a C$30 million fine for advertising vehicle rental prices that were unattainable due to additional “non-optional fees.” 
• In 2023, Experian Consumer Services faced a $650K fine for sending emails claiming to contain important account information while promoting commercial products​. 

Recent legal cases 

More recently, there have been instances of legal action taken against brands specifically for using misleading subject lines. For example, creating a false sense of urgency by claiming ‘Sale ends at midnight,’ only for the promotion to continue for another three days. 

• Earlier this year, the Washington State Court ruled in Brown v. Old Navy that any false or misleading information in an email subject line sent to a Washington resident violates the state’s Commercial Electronic Mail Act (CEMA).  
• A similar lawsuit was filed against Nike, claiming their marketing emails “contain subject lines designed to impart a false urgency or false sense of scarcity for products to pressure consumers into making more immediate purchasing decisions.” 

 Professional complainers know the rules 

It’s surprising this didn’t happen sooner. Legislation all over the world is consistently clear on this topic, and “professional complainers” may see this as their next big opportunity. 

Here are just a few of the relevant laws at play: 

• CAN-SPAM*: FTC guidance leaves no room for doubt. Subject lines should accurately reflect the email’s content and not be deceptive in a way that could mislead recipients about the message’s subject matter.
  *While CAN-SPAM preempts state laws regulating the use of commercial emails, an exception exists for state laws to prohibit material falsity or deception in commercial emails, giving rise to Washington State’s CEMA law, and California’s anti-spam law, among others.
• GDPR*: In the UK, the Information Commissioner’s Office is clear that businesses must use personal data in a fair way. This means not processing it in a way that is unduly detrimental, unexpected, or misleading to recipients.
  *Following the United Kingdom’s exit from the European Union in January 2020, it has adopted the UK GDPR. At present, this is largely similar to its EU counterpart but may diverge over time. 

How much will a slip-up cost you? 

Non-compliance can be extremely costly. Under CAN-SPAM, each separate email violating the act is subject to penalties of up to $53K. Under CEMA, damages are set at $500 per message, or actual damages—whichever is greater.

Violations of California’s anti-spam laws can result in civil penalties including actual damages, liquidated damages (up to $1,000 per email, with a maximum of $1M per incident), and attorney’s fees. GDPR is notorious for potential fines that rise to €20 million or four percent of global annual turnover, whichever is higher.  

The new anti-spam laws in Washington, California, and other states also raise the bar for email marketers in other ways, as this article from Performline states: 

• Stricter liability means intent doesn’t matter—if a subject line is misleading, it’s a violation. 
• Statewide jurisdiction covers all residents, regardless of where the email originated. 
• Plaintiffs don’t need to prove that damages were incurred. 
• Volume magnifies risk, so small mistakes can become expensive fast. 

Mailbox providers don’t like them either  

Mailbox providers (MBPs) also have strong feelings about the use of misleading subject lines, and their guidance to email marketers is crystal clear: 

• Gmail: Email message subject, headers, display names, and other elements should accurately represent the sender’s identity and message content—and shouldn’t be misleading.  
• Yahoo: Don’t use false or misleading header information or deceptive subject lines to hide, forge, or misrepresent the sender or origin of the email. 
• Microsoft: Use accurate subject lines, avoid deceptive headers, and ensure your recipients have consented to receive your messages.   

These MBPs will take negative action—including filtering and blocking—in response to the use of misleading subject lines, especially as artificial intelligence improves their ability to compare email subject lines with the corresponding content. 

What NOT to do when writing subject lines

While we have already looked at examples of subject lines referencing shifting sale deadlines and non-existent price discounts, there are many other ways email subject lines can mislead. 

• Implying a false existing relationship: Using “FW” and “RE” when you haven’t had prior contact.  
• Suggesting engagement that didn’t actually happen: Using phrases like “Guy, Did You Forget Something?” to mimic basket abandonment (it was a Black Friday email!). 
• Embroidered empathy: Saying things like “We miss you!” (Er, no, I don’t think you do really. You miss my wallet, maybe, but not me!) 
• Fake mistakes: email marketers know apology emails drive great engagement, and it’s tempting to mimic this approach for other messages. Things like “OOPS! We Did WHAT?!” actually reference a 50 percent-off promotion they nearly forgot to share! 
• Creating unwarranted fear: Including phrases like “Your account status” when the email is just asking the recipient to start a new free trial. 
• Hinting at preferential treatment: Making claims like “You’ve achieved PREMIUM status. Upgrade now!”) (Um, that’s great, but you really mean I’ve still got to pay for it?)  
• Making promises that are almost certainly unachievable: E.g., “Better than any probiotic you’ve ever tried—GUARANTEED” when such an outcome is largely subjective.  
• Almost any form of clickbait: Typically referring to the practice of writing sensationalized or misleading headlines to attract opens and clicks. 

How to keep yourself honest 

So, we’re clear that the use of misleading subject lines is a really bad idea. Your customers hate them, mailbox providers hate them, and there is a significant risk of incurring big fines!

But misleading subject lines aren’t always used intentionally. So, how can senders avoid them?  

• Remember that honesty is the best policy and practice it! Ensure your subject lines accurately reflect what your customers will see when they open your messages and click through to your website. 
• Use competitive intelligence tools like Validity MailCharts to get a feel for which subject lines are working best, and what words and phrases are trending. 
• Beware of unintended outcomes from using AI. The Litmus State of Email 2025 report states that the use of generative tools for content creation is email marketers’ most-used AI capability. Double check outputs to ensure they are both ethical and legal. 
• Use GPT assistants to do the checking for you. Provide them with your subject line, your content, and the court cases and best practices referenced in this post. Request feedback on whether there is any risk of non-compliance. 
• Make regular use of subject line testing. The way your test subjects respond will quickly flag if the version you’ve drafted will have them engaging positively or negatively. 
• Embrace negative metrics like opt-outs and spam complaints. Your customers are providing valuable feedback—often prompted by subject lines—their first touch point with each new message they receive.  
• Register to receive the FTC’s newsletter, which has updates on all the latest law enforcement actions. ClassAction.org’s newsletter and ICO’s newsletter for UK readers are also good resources. 
• Finally, take a moment to walk a mile in your customers’ shoes. Ask yourself how you would respond as a consumer when receiving your messages. If your gut response is “not great,” then fix them. 

Put your subject lines to the test  

Subject lines are a critical part of email marketing success. Use them responsibly, respect your customers, and watch your subscriber engagement and program revenue head into the stratosphere! 

Want to see how your subject lines will appear in subscribers’ inboxes, without spending hours on reviews and QA? Litmus from Validity lets users preview emails in 100+ clients, catch errors, and ensure accessibility—all while cutting QA time in half.