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What is the difference between opt-in and opt-out email?

Also called: opt-in permission marketing, email consent, Opt-In Permission Marketing (B2B)

Opt-in means a person agrees before you email them; opt-out means you may email them until they ask you to stop. U.S. law (CAN-SPAM) is an opt-out system, while Canada's CASL is largely opt-in and the UK and EU have their own rules.

By John Britton, VP of Marketing, MedicalProspects · Updated November 4, 2026 · Compliance

Why it matters for healthcare sales and marketing

Whether you need consent before the first email depends on where the recipient is. Getting it wrong can mean regulatory risk and complaints, and ignoring opt-outs is a violation almost everywhere.

How it works

  • United States (CAN-SPAM): opt-out. You can send commercial email without prior consent, but you must honor opt-outs within 10 business days.
  • Canada (CASL): largely opt-in. You generally need express or implied consent, with limited exceptions, for example for addresses conspicuously published for business with no "no marketing" statement, when the message relates to the person's role.
  • United Kingdom (UK GDPR and PECR): B2B emails to corporate addresses can rely on legitimate interests with a clear opt-out; individual and sole-trader addresses need consent.
  • European Union (GDPR plus national laws): varies by country; some, such as Germany, restrict unsolicited B2B email more tightly.

Everywhere: identify yourself, include an opt-out, and keep one suppression list across all your tools.

Cards comparing email consent rules: United States (CAN-SPAM, opt-out), Canada (CASL, mostly opt-in), United Kingdom (GDPR and PECR, corporate B2B with opt-out), and European Union (varies by country).
Consent rules for B2B email depend on the recipient's country. General information, not legal advice.

Example

Illustrative scenario. A company emailing physicians in the U.S. and Canada splits its list by country. U.S. contacts get its standard CAN-SPAM-compliant campaign. Canadian contacts only receive email where the company can document consent or a valid exception, and everyone else is invited to opt in through other channels.

Common mistakes

  • Using U.S. rules everywhere. Check the recipient's country.
  • Separate suppression lists per tool. An opt-out must apply everywhere you send from.
  • Assuming B2B is always exempt. It isn't under CASL, and EU rules vary.
  • Hiding the opt-out. Make it clear and easy.

Related terms

  • CAN-SPAM ActThe CAN-SPAM Act is the U.S. law that sets the rules for commercial email, including business-to-business email. It doesn't require prior consent, but it does require honest sender information and subject lines, a physical postal address, a working opt-out, and handling opt-outs within 10 business days.
  • CASL (Canada's Anti-Spam Legislation)CASL is Canada's Anti-Spam Legislation. It generally requires consent, express or implied, before sending commercial electronic messages, along with sender identification and a working unsubscribe, and it applies to B2B email sent to recipients in Canada.
  • UK GDPR and PECRIn the UK, B2B email marketing is governed by PECR, which sets the rules for electronic marketing, and by UK GDPR, which governs the personal data involved. Emails to corporate addresses don't need prior consent under PECR but must identify the sender and offer an opt-out; individual and sole-trader addresses generally need consent.
  • Suppression ListA suppression list is the set of email addresses you must never send to, such as people who unsubscribed, addresses that hard-bounced and people who marked your email as spam. It should apply across every tool and campaign you send from.
  • HIPAA and B2B Healthcare OutreachHIPAA protects patients' health information held by health plans, healthcare clearinghouses, most healthcare providers and their business associates. A clinician's professional contact details are not patient health information, so B2B email to healthcare professionals is governed by marketing laws such as CAN-SPAM rather than by HIPAA.

Put it to work

Sources

  1. CAN-SPAM Act: A Compliance Guide for Business, Federal Trade Commission
  2. Canada's Anti-Spam Legislation, CRTC
  3. Guide to PECR: electronic mail marketing, Information Commissioner's Office

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