Is ZoomInfo's interpretation of CAN-SPAM accurate regarding email marketing best practices?
Matthew Whittaker
Co-founder & CTO, Suped
Published 10 Jun 2025
Updated 16 Aug 2025
7 min read
The world of email marketing is constantly evolving, and staying compliant with regulations like the CAN-SPAM Act is crucial. However, navigating these regulations can be complex, and misunderstandings often arise. Recently, I encountered a claim from ZoomInfo that sparked significant discussion among email professionals, particularly regarding the need for opt-in consent for email campaigns. The statement essentially argued that as long as an unsubscribe option is provided, sending emails is permissible under CAN-SPAM, implying that specific opt-in permission isn't necessary for commercial messages.
This interpretation, while technically aligning with a narrow reading of the CAN-SPAM Act's specific legal requirements for commercial email, significantly overlooks critical aspects of email deliverability and broader industry best practices. It's a common point of contention, especially for those who rely on purchased lists or cold outreach.
My goal here is to dissect this claim, clarify what CAN-SPAM actually mandates, and explain why adhering only to the bare minimum of the law can lead to severe deliverability problems, regardless of legal compliance. It is important to look at the full picture of how email ecosystems operate, from legal frameworks to the policies of email service providers (ESPs) and mailbox providers.
The CAN-SPAM Act: what it actually says
The CAN-SPAM Act, enacted in 2003, is the US law that sets the rules for commercial email. It applies to all commercial messages, which the law defines as "any electronic mail message the primary purpose of which is the commercial advertisement or promotion of a commercial product or service." This includes B2B emails, not just B2C. The Federal Trade Commission (FTC) provides a comprehensive compliance guide on their website.
Key requirements of CAN-SPAM include providing a clear and conspicuous way for recipients to opt out of future emails, including a valid physical postal address, and using non-deceptive subject lines and headers. It does not, however, explicitly require prior consent or an opt-in for commercial emails to be sent, which is where ZoomInfo's interpretation stems from. This is a crucial distinction between US law and, for example, the GDPR in Europe, which has much stricter consent requirements.
While CAN-SPAM doesn't mandate opt-in, it also doesn't prohibit mailbox providers or ESPs from enforcing their own stricter policies. This legal loophole is often exploited, leading to a significant disconnect between what is legally permissible and what is effective or desirable for email marketing. Just because something isn't illegal doesn't mean it's good practice or won't cause deliverability issues. For more on what constitutes an illegal spam tactic, see my article: Are cold outreach 'best practices' actually illegal spam tactics?
Key CAN-SPAM requirements
Truthful headers: Don't use misleading or inaccurate routing information.
Relevant subject lines: Ensure the subject line accurately reflects the email content.
Ad disclosure: Clearly state if the message is an advertisement.
Physical address: Include your valid physical postal address.
Easy opt-out: Provide a clear and functional unsubscribe mechanism.
Timely opt-out processing: Honor opt-out requests within 10 business days.
Beyond the law: ESPs and mailbox providers
Here's where ZoomInfo's interpretation falls short of genuine email marketing best practices. While the CAN-SPAM Act might allow sending commercial emails without prior opt-in, Email Service Providers (ESPs) like Mailchimp, HubSpot, and others have far stricter Acceptable Use Policies (AUPs). These policies are designed to protect their shared sending infrastructure and ensure high deliverability rates for all their customers. Ignoring these policies can lead to immediate account suspension, regardless of CAN-SPAM compliance.
Mailbox providers (like Gmail, Outlook, and Yahoo) also have sophisticated spam filters that go far beyond legal compliance. These filters analyze engagement, sender reputation, and complaint rates. If recipients consistently mark your emails as spam, even if you offer an unsubscribe link, your sender reputation will plummet, leading to your emails landing in the spam folder or being blocklisted (blacklisted). This can severely damage your ability to reach anyone's inbox, regardless of whether your emails are legally compliant. Learning what are the best practices for email deliverability is essential.
The policies of ESPs and mailbox providers are not arbitrary, nor are they simply to cover their behinds. They exist to maintain the health and integrity of the email ecosystem. A high volume of unwanted emails leads to increased spam complaints, lower engagement rates, and ultimately, poor deliverability for everyone. This is why many reputable ESPs explicitly prohibit the use of purchased or scraped email lists, even if they contain business contacts.
Legal compliance
Focuses on meeting minimum legal requirements like providing an unsubscribe link and physical address as per CAN-SPAM. The absence of explicit opt-in is not a legal violation in the US for commercial emails, as long as other rules are followed. This approach often prioritizes quantity over quality in lead acquisition.
Reputation and deliverability
Adhering only to CAN-SPAM can still result in low inbox placement rates if recipients report your emails as spam. This can lead to your domain or IP being added to a blocklist (or blacklist), making it difficult to send any emails, including legitimate ones. Your sender reputation suffers greatly, impacting future campaigns. Learn how to recover domain reputation.
Email marketing best practices
Goes beyond legal minimums to ensure high engagement and inbox placement. This includes obtaining explicit consent (opt-in) from recipients, segmenting lists, personalizing content, and monitoring engagement. This approach focuses on building a quality audience that wants to receive your emails. You can check MarTech for more insights on best practices.
Recipient experience
Prioritizes delivering value to recipients who expect and want your emails. This leads to higher open rates, click-through rates, and conversions. A positive recipient experience reduces spam complaints and helps build a strong sender reputation, ensuring long-term email marketing success.
The impact of purchased lists on deliverability
The primary issue with relying solely on the CAN-SPAM Act's opt-out provision, especially when using lists obtained from sources like ZoomInfo, is the high risk of damaging your sender reputation. While ZoomInfo's data might include valid email addresses, these recipients have not explicitly consented to receive your marketing messages. This lack of consent is a major red flag for mailbox providers.
When you send emails to un-opted-in recipients, you risk triggering spam traps. Spam traps are email addresses used by mailbox providers and blocklist (or blacklist) operators to identify senders of unsolicited bulk email. Hitting spam traps indicates that your list quality is poor and can swiftly lead to your IP address or domain being added to a blocklist, causing severe deliverability problems. My article on spam traps provides more detail.
Even if the addresses are legitimate, high bounce rates (due to outdated data) and low engagement (due to irrelevance) will harm your sender reputation. Mailbox providers interpret these signals as indications of unwanted mail, moving your emails to the spam folder or outright rejecting them. This is a common reason why your emails go to spam. Maintaining a clean, opted-in list is fundamental to good deliverability and avoiding such issues. For information on how your email can end up on a blocklist, read how your email address ends up on a blacklist.
Factor
Impact of Opt-In lists
Impact of Purchased lists
Spam complaints
Very low, as recipients expect your emails.
High, leading to poor sender reputation and blocklists.
Engagement rates
High, with better open, click, and conversion rates.
Low, as recipients are often uninterested.
Deliverability
Excellent, with emails consistently reaching the inbox.
Poor, with emails landing in spam or being rejected.
While ZoomInfo's interpretation of CAN-SPAM is technically correct in that the law doesn't explicitly require opt-in, it's a dangerous simplification when it comes to effective email marketing and deliverability. Relying solely on the legal minimum sets you up for deliverability challenges, including high spam complaint rates, damage to your sender reputation, and potential account suspension by your ESP.
The best practice is always to obtain explicit consent (opt-in) from your recipients. This ensures that your audience genuinely wants to receive your emails, leading to higher engagement, better inbox placement, and sustainable email marketing success. Prioritizing legal compliance alongside robust deliverability strategies is key for any responsible sender. If you want to know what to do when your company prioritizes short-term spam gains, check out my other article.
Views from the trenches
Best practices
Always prioritize explicit opt-in for email lists to ensure high engagement and deliverability.
Regularly clean your email lists to remove inactive subscribers and potential spam traps.
Monitor your sender reputation and deliverability metrics actively to catch issues early.
Align your email practices with your ESP's terms of service and mailbox provider expectations.
Segment your audience and personalize content to increase relevance and reduce spam complaints.
Common pitfalls
Relying solely on CAN-SPAM's legal minimums without considering broader deliverability factors.
Using purchased or scraped email lists, even if they appear legally compliant, due to deliverability risks.
Ignoring high bounce rates or low engagement, which signal poor list quality and sender reputation issues.
Believing that an unsubscribe link alone guarantees inbox placement or compliance with all policies.
Failing to understand that ESP and mailbox provider policies are crucial for successful email delivery.
Expert tips
ESPs have their own stringent rules to protect their network reputation, which often go beyond legal mandates.
Mailbox providers use complex algorithms that penalize low engagement and high complaint rates.
A high volume of unwanted emails can lead to IP and domain blocklisting (blacklisting), severely impacting all email.
Protecting your sender reputation is more important for deliverability than merely avoiding legal infractions.
Focus on building relationships with recipients who genuinely want your emails for long-term success.
Marketer view
A marketer from Email Geeks says that while it may not be illegal, sending emails based on the ZoomInfo interpretation is against the terms of use agreed upon with email service providers.
2021-09-24 - Email Geeks
Expert view
An expert from Email Geeks explains that CAN-SPAM is not the only consideration, as ESP policies are critical for successful message delivery to recipients' inboxes.
Mailchimp, 
HubSpot, and others have far stricter Acceptable Use Policies (AUPs). These policies are designed to protect their shared sending infrastructure and ensure high deliverability rates for all their customers. Ignoring these policies can lead to immediate account suspension, regardless of CAN-SPAM compliance.
Gmail, 
Outlook, and 
Yahoo) also have sophisticated spam filters that go far beyond legal compliance. These filters analyze engagement, sender reputation, and complaint rates. If recipients consistently mark your emails as spam, even if you offer an unsubscribe link, your sender reputation will plummet, leading to your emails landing in the spam folder or being blocklisted (blacklisted). This can severely damage your ability to reach anyone's inbox, regardless of whether your emails are legally compliant. Learning what are the best practices for email deliverability is essential.
