You send a campaign to your Canadian subscribers, but half the emails bounce. Not because of invalid addresses—but because consent expired. You thought you were safe, but now you're facing compliance risk.

Under Canada’s Anti-Spam Legislation (CASL), implied consent doesn’t last forever. It expires after 24 months of inactivity. If someone hasn’t engaged with your emails in two years, you no longer have a legal basis to send to them—regardless of how you acquired the address. This isn’t a suggestion. It’s a boundary.

Whether you’re sending from Toronto, Vancouver, or across the border, if your emails target Canadian residents, CASL applies. Ignoring the 24-month rule isn’t just risky—it’s a common point of failure for even large marketers.

Key takeaways

  • Implied consent under CASL automatically expires after 24 months of no engagement with your emails.
  • Even if you collected an email legally, you must reconfirm consent if the recipient hasn’t opened, clicked, or otherwise engaged in two years.
  • Non-compliance can result in fines up to CAD $1 million per violation, making verification of engagement status a critical part of compliance.

Under Canada’s CASL, implied consent allows you to send commercial emails if someone gave you their email in connection with a transaction or ongoing offer—like buying a product online. This consent lasts up to 24 months from the last interaction, but only if your messages stay relevant and you maintain engagement. If a contact never opens or interacts with your emails, that consent expires early.

Let’s say you run a Canadian e-commerce store and a customer buys a coffee maker from your website. That purchase creates implied consent under CASL, meaning you can send order confirmations, shipping updates, shipping tracking links, and even follow-ups about product care—all as part of the transaction. The law sees this as reasonable and expected by the user.

But this doesn’t mean you can send unrelated promotions six months later. The connection between the original transaction and your emails must remain clear and relevant. If you send a newsletter about winter apparel to somebody who bought a coffee machine in June, that breaks the implied consent principle.

Implied consent doesn’t last forever. It can expire if there’s no engagement for more than 24 months from the last interaction. But even before that, silence or inactivity breaks the connection. If a customer never opens your emails, they’re not engaging—and that weakens the basis for further communication.

Think of it like a handshake: it’s valid right after the transaction, but if you don’t stay in touch, the relationship fades. The rules don’t require you to check in every month—but they do demand relevance and responsiveness.

For example, a customer who bought a subscription last year and hasn’t opened one email in the past 18 months likely no longer consents to further messages. Sending them a new offer at that point is a high-risk move under CASL, even if it’s within the 24-month window.

For teams managing large email lists, this creates real urgency: verifying list quality and removing inactive addresses is not just good practice—it’s a compliance necessity. You can test deliverability and inbox placement with real-world feedback before sending, helping you avoid bounces and spam traps. MailTester’s inbox placement tester gives you real insights into how your emails land in actual inboxes—without sending anything to your entire list first. Test your delivery now.

The bottom line: implied consent under CASL is time-limited and engagement-dependent. You have a window—up to 24 months—but it narrows fast if your emails don’t matter to the recipient. Keep your communications relevant, test your inbox placement, and clean your list regularly to stay compliant. For tools that help you verify email validity and detect inactive or risky addresses, check out MailTester’s bulk verification or our real-time API.

Under Canada’s Anti-Spam Legislation (CASL), you must refresh consent every 24 months if there’s been no meaningful engagement. After this period, the law assumes consent has lapsed due to inactivity, making continued email communication non-compliant without explicit re-consent.

What "No Interaction" Really Means

Let’s be clear: the 24-month rule isn’t about when the last email was sent. It’s about whether your audience has actively engaged—opened, clicked, or responded—within that window. If they haven’t, that’s a reliable signal that interest has faded.

Consider this: if your list includes emails that haven’t opened a message in over two years, it’s highly likely those recipients no longer want to hear from you. Sending to them—even with a “clean” list—carries a real risk of violating CASL. The law treats inactivity as a loss of implied consent.

Why 24 Months? The Logic Behind the Number

24 months aligns with industry norms for engagement cycles. Most marketing teams treat a year as a benchmark for re-engagement. Extending it to two years accounts for seasonal gaps, personal circumstances, and natural email fatigue.

Beyond that, the risk of non-compliance rises sharply. The Canadian Radio-television and Telecommunications Commission (CRTC) has made it clear that maintaining consent is not automatic. Their enforcement approach treats dormant lists as high-risk. CRTC guidance stresses that continued outreach without active consent is a violation, even if the email address is technically valid.

Let’s say you have a subscriber who joined your list in January 2022 and hasn’t opened a single email since. You can’t assume they still want your content. You must either re-verify their intent or remove them. Otherwise, you’re sending unsolicited messages—directly contravening CASL.

Tools like MailTester’s bulk verification help flag inactive addresses before they become compliance liabilities. It’s not just about catching bad domains—it’s about identifying lists where engagement has dropped off over time.

You risk fines of up to $1 million per violation under CASL if you send emails to contacts whose implied consent has expired after 24 months of inactivity. Even one non-compliant message can trigger spam filters, tank your sender reputation, and hurt deliverability for months — or longer. Let’s break down why ignoring this rule matters.

Penalties Are Real and Severe

Canada’s Anti-Spam Law (CASL) doesn’t leave much room for error. Sending marketing emails to inactive contacts who haven’t engaged in 24 months breaches implied consent rules. The penalties aren’t theoretical: the Canadian Radio-television and Telecommunications Commission (CRTC) has fined businesses up to $1 million for single violations. That’s not a risk you can afford to ignore.

Spam Filters Don’t Care About Intent

Even if you believe your campaign is legitimate, sending to expired consent lists often triggers ISP spam filters. Gmail, Outlook, and other major providers monitor engagement patterns. If your list contains old, unresponsive addresses, your messages are more likely to land in spam, be quarantined, or never reach inboxes at all.

And once your domain starts getting flagged for low engagement, reputation tools like SenderScore or Google’s Postmaster Tools mark you as risky. That reputation affects all future sends — not just the ones that broke the rules.

Damage Is Cumulative and Hard to Reverse

High bounce rates from invalid or inactive addresses degrade your sender reputation over time. ISPs treat consistent bounces as a sign of poor list hygiene. The longer you ignore it, the harder it becomes to rebuild trust. Even if you clean your list later, the damage compounds across your IP and domain reputation.

For example, a single spike in bounces can trigger temporary blocks. Reputations recover slowly — sometimes taking months — especially if you’re not actively monitoring deliverability metrics and list health. You’re not just risking one email; you’re risking your entire email program.

To stay compliant and maintain inbox placement, regularly verify your list for validity and engagement. Tools like MailTester’s bulk verification can identify inactive, invalid, or risky addresses before you send. Using the inbox placement tool helps you audit real-world deliverability across Gmail, Outlook, and other major providers.

MailTester’s API also integrates directly with your CRM or ESP, so you can validate contacts in real time — before they ever hit a send. This kind of proactive hygiene is the only way to scale safely under CASL and avoid long-term delivery failures.

Under CASL, implied consent expires after 24 months of no engagement. Review your engagement logs and flag any contact who hasn’t opened, clicked, or interacted with your emails in that time. Remove those with zero engagement entirely — they never had valid consent. Segment your list by last interaction date to clearly separate active subscribers from those whose consent has lapsed.

Step-by-Step: Flag and Clean Your List

  • Export your email list with engagement metrics — last open, last click, and first engagement date.
  • Filter contacts where the last engagement was more than 24 months ago. These are no longer under implied consent.
  • Exclude any contact who has never engaged — even if they’ve been on your list for years, they fall outside CASL’s implied consent rules.
  • Use your ESP or CRM to create a segment for “Inactive for 24+ Months” — this becomes your cleanup target.
  • Run a one-time verification check using the MailTester bulk verification to catch invalid or disposable emails before you remove them.

Verify Before You Remove

Even a 24-month inactive list may include inactive but valid emails. Use real-time validation to ensure you're not dropping valid contacts due to outdated metadata. This is especially important if you’ve inherited a list from another sender.

The MailTester verification report shows exactly which addresses are valid, risky, or catch-all — so you can remove obsolete entries with confidence. No guesses, no false positives.

  • Run your list through the MailTester API to catch any catch-alls or role addresses that might skew your engagement metrics.
  • Look for domains known for high disposable email use (like tempmail.org) — these are not valid long-term subscribers.
  • Segment your list not just by age, but by engagement behavior: last open, click frequency, and list source.
  • Store the cleaned list in a separate segment labeled “CASL-Compliant” — it’s easier to track and audit.
  • Rebuild your engagement campaigns using only the active or recently re-engaged segment.
“CASL’s implied consent rule is strict: no interaction for 24 months? No consent.” — Canadian Anti-Spam Legislation, Industry Canada.

Consent isn’t static. It needs regular review. A list that hasn’t triggered a single open or click in over two years is no longer compliant. Use MailTester to verify and segment — not just to remove, but to maintain accuracy, reputation, and deliverability. You’ll lower your bounce rate, improve your sender score, and avoid fines.

The Role of Email Verification in Maintaining CASL Compliance

Under CASL, implied consent lasts up to 24 months, but sending to invalid, role-based, or disposable emails increases bounce rates and can signal spam behavior, risking compliance. Email verification removes these addresses before sending, protecting your sender reputation and ensuring only valid, consented contacts receive your messages. This proactive cleanup helps avoid scrutiny from regulators and inbox providers alike.

Why Invalid Addresses Break CASL Rules

Role accounts (like info@ or sales@), disposable emails, and typosquatting addresses don’t represent real users. Sending to them increases bounce rates, which can trigger spam filters and raise red flags with enforcement bodies. High bounce rates over time are seen as signs of poor list hygiene, especially under strict regimes like CASL.

For example, even a 2% bounce rate over time can attract unwanted attention from email providers, especially when combined with other deliverability red flags. As outlined in industry guidance from the Spamhaus Project, senders with consistent high bounce rates are more likely to be flagged, blocked, or reported.

How Verification Sustains Compliant Sending

Using a tool like MailTester’s bulk verification API lets you test large lists quickly and accurately, identifying invalid emails, catch-all domains, and risky addresses before they hurt your send rate. This isn’t just about reducing bounces—it’s about proving you’re actively maintaining list quality, which supports your compliance posture under CASL.

Let’s say you have a list that’s grown stale over 18 months. Sending without verifying means risking consent timelines and damaging sender reputation. With MailTester’s bulk verification, you can clean your list in minutes and keep only deliverable, valid addresses—those most likely to have ongoing consent.

For those sending programmatically, our verification API integrates directly into your onboarding or engagement workflows, ensuring you only add verified, compliant emails. When combined with inbox placement testing via inbox tester, you confirm not just address validity, but whether your message is landing in the inbox—where it belongs.

CASL isn’t just about consent—it’s about responsible sending. Verification is a practical, measurable step toward that goal. By preventing sends to non-existent or non-consenting addresses, you reduce risk, improve deliverability, and strengthen trust. It’s not a checkbox—it’s part of sustainable, compliant email practices. With 100 free verifications to start, testing your list is low-cost, low-risk, and high-impact.

Step-by-Step: Cleaning Your List for CASL Compliance

Start by exporting your email list and pulling engagement data from the past 24 months—this is the only way to prove implied consent under CASL. Then, verify every address using a tool like MailTester to eliminate invalid, catch-all, and risky emails. Segment based on opens or clicks within that window, re-engage inactive users only if they previously consented, and purge all non-engaged, unverified, or role-based addresses. This keeps your list compliant, deliverable, and legally defensible.

Process: Preparing Your List for Compliance

  1. Export your list and pull 24-month engagement data. CASL requires that consent be demonstrable. Only contacts who opened or clicked within the past 24 months can be considered to have implied consent. Use your ESP or CRM to export open/click records. If you lack this data, treat the entire list as non-compliant.
  2. Run the list through an email verification tool like MailTester. Use the bulk verification feature to check for undeliverable addresses, catch-all inboxes, and disposable domains. This step removes technical noise that could result in hard bounces and harm sender reputation. MailTester catches more than 98% of invalid addresses with real-time SMTP checks.
  3. Segment by engagement activity. Split your list into two groups: those who engaged in the past 24 months (opens or clicks), and those who didn’t. Only the engaged segment qualifies for continued messaging under CASL—if they consented, you can re-engage. The unengaged group needs to be removed unless you have explicit opt-in.
  4. Send a re-engagement campaign to non-active, consented users. If a subscriber previously consented, send one re-engagement message to revive interest. Include a clear unsubscribe option. Monitor deliverability and response rate. If they don’t engage within 30 days, remove them from the list.
  5. Remove non-compliant, unverified, or role-based addresses. Eliminate all addresses that failed verification, are role-based (e.g., sales@, info@), or have no activity. Role accounts are not considered valid for consent under CASL and often trigger spam filters. Never keep them on your list.

Why This Matters

Under CASL, sending to anyone outside your active, engaged list risks severe penalties. The Canadian Radio-television and Telecommunications Commission (CRTC) enforces strict rules on consent. You must prove you have a valid relationship with every recipient. According to the CRTC’s guidelines, failing to comply can result in fines of up to $1 million per violation.

Using tools like MailTester ensures you’re not sending to dead or high-risk addresses. An integration with platforms like Mailchimp or Klaviyo can automate this cleanup before every campaign. This isn’t just about avoiding bounces—it’s about being legally sound. Keep your list lean, clean, and compliant. Your inbox placement and sender reputation will thank you.

Why You Shouldn’t Trust Your List’s ‘Active’ Status Alone

Just because your CRM marks an email as “active” doesn’t mean it’s actually valid or deliverable. Many systems count opens based solely on tracking pixels, which can fail silently—especially if a user disables images or uses a privacy-focused email client. That’s why you need email verification: it confirms the address is real and can receive mail, regardless of whether tracking works. Even the most active-looking list can be full of dead or invalid addresses.

Tracking Pixels Lie (and Break)

Most CRMs assume an open if a pixel loads. But that pixel only fires if images are enabled. On average, over 50% of email clients now block images by default, particularly in privacy-focused inboxes like ProtonMail or Apple Mail’s default settings. Even if someone reads your email, the pixel might never load. So you’re left with a false signal: your system says “active,” but the address could be invalid, a catch-all, or even a placeholder.

It gets worse: some users never see your email at all. A malformed address, one with typos, or a role account like admin@ might be flagged as “active” but will bounce silently. Or they might catch-all, absorbing your message without a single complaint. These are not engaged customers—they’re just invisible drains on your deliverability.

Verification Proves What Tracking Can’t

That’s where email verification comes in. Tools like MailTester’s bulk verification don’t rely on pixel tracking. They check the underlying mailbox, domain, and DNS records—testing whether an email address is actually deliverable. This works even if images are disabled, if tracking fails, or if a campaign never lands in the inbox. A valid address today may be invalid tomorrow, and only proactive verification keeps your list clean.

Verification also identifies risky or disposable domains, catch-all addresses, and role accounts—all of which inflate your “active” count without helping conversions. According to RFC 5321, a valid SMTP transaction requires a working recipient, not just a read signal. So while your CRM may celebrate a high open rate, your deliverability could still be sinking.

Let’s be honest: you can’t optimize email deliverability on the assumption that “active” means “real.” The only way to know for sure is to test each address directly. MailTester’s inbox placement tests mimic real inboxes and confirm whether your emails actually land in the inbox, not the spam folder—giving you data, not guesses. And with a 98.9% accuracy rate, it’s one of the most trusted tools in the deliverability space.

How MailTester Helps Stay CASL-Compliant on a Large Scale

You can maintain CASL compliance on large lists by verifying every email address in real time with 98.9% accuracy, catching invalid, role-based, catch-all, and disposable addresses before they get sent. This reduces bounce rates, protects sender reputation, and ensures only valid, consented contacts are reached—critical for meeting the 24-month implied consent window under CASL.

Real-Time Verification to Prevent Non-Compliant Sends

MailTester checks each address using live SMTP connections and DNS validation, confirming not just syntax but actual deliverability. This isn’t heuristic guesswork—it’s a direct test of whether an inbox exists and will accept messages. This level of certainty lets you exclude addresses that are likely to bounce or trigger spam filters, which is especially important when managing long-term engagement windows like CASL’s 24 months.

CASL requires that consent be verifiable. If you’re sending to an address that doesn’t respond or doesn’t exist, you’re violating the spirit of the law. MailTester eliminates this risk by flagging non-receivers early—before any message goes out.

Automated Cleanups Across Your Marketing Tools

With integrations into Mailchimp, Klaviyo, SendGrid, and HubSpot, you can automatically verify lists before sending. You don’t have to manually scrub data every time you run a campaign. Instead, the system checks all new or active contacts in real time and removes problematic addresses—such as info@, sales@, or [email protected]—before they ever hit your campaign.

Role accounts and disposable domains often show up on lists with high bounce rates and poor engagement. Under CASL, a consistent failure to deliver to a significant number of addresses could undermine the assumption of implied consent. MailTester removes these addresses, making your list more reliable and helping maintain a healthy sender reputation. Over time, this consistency strengthens your compliance posture.

For organizations managing hundreds of thousands of contacts, manual checks are impractical. With MailTester’s bulk verification, you can process entire lists in minutes. Start with 100 free verifications, and keep using credits indefinitely—no expiry. See how it works: bulk list verification, or integrate via the real-time API.

The technical foundations of deliverability—SPF, DKIM, DMARC—are only one piece. True compliance comes down to sending only to valid, consented inboxes. MailTester helps you do that at scale, with accuracy that’s validated in practice, not just in theory.

Bonus: The Long-Term Payoff of a Clean, Verified List

Every verified email reduces bounce risk and spam complaints—two key signals ISPs use to evaluate sender reputation.

Over time, a list that stays clean enables consistent inbox placement, even after 24 months of sustained campaigns under CASL’s implied consent rules.

Why verification matters beyond compliance

  • Engaged recipients are more likely to open, click, and convert—directly improving campaign ROI.
  • Low bounce and complaint rates help maintain a strong sender reputation, which ISPs reward with better inbox placement.
  • Only valid, active addresses receive your messages, reducing wasted sends and improving overall deliverability.

Sources

Keep reading

Ready to put this into practice? MailTester verifies emails with 98.9% accuracy — start with 100 free verifications.

Frequently asked questions

Yes. Under CASL, implied consent expires after 24 months of inactivity. If a contact hasn’t engaged with your emails in two years, you must regain consent before sending again.

Can I send emails to someone who hasn’t engaged in 23 months?

Yes. As long as the last engagement was within the 24-month window, sending is compliant under CASL. After that, you must reconfirm consent.

You risk fines up to $1 million per violation. Your domain may also be flagged by ISPs, leading to email delivery issues.

Do role-based email addresses break CASL rules?

Role accounts (e.g. support@, admin@) don’t constitute valid consent. They are high-risk and should be removed from your list.

No. Disposable emails (like tempmail.com) are not considered valid consent under CASL and often lead to high bounce and spam rates.

How accurate is MailTester’s email verification?

MailTester achieves 98.9% accuracy in verifying email addresses using real-time SMTP checks and DNS analysis.

Do verifications expire on purchased credits?

No. Credits purchased on MailTester never expire, allowing you to verify lists at any time without time pressure.

Can I use MailTester with HubSpot or Mailchimp?

Yes. MailTester integrates with HubSpot, Mailchimp, Klaviyo, and SendGrid to automatically verify emails before sending.

Should I verify my list every time before sending?

Yes. Regular verification ensures high deliverability and ongoing compliance, especially as lists age and change.

Is an email still valid if it bounces after 3 weeks?

No. A bounce after initial delivery often signals a broken or inactive address. These should be removed immediately to preserve sender reputation.

Implied consent arises from a transaction; express consent requires a clear, opt-in action like a double opt-in checkbox.

How do greylisting and catch-all domains affect CASL compliance?

Catch-all domains accept all emails, making them unreliable. Greylisting can delay delivery but doesn’t affect compliance — just deliverability.