Understanding explicit vs. implicit consent

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You will learn

Learn more about the different types of consent (explicit vs. implicit) in Klaviyo and who you can or cannot email. Being able to email a subscriber basically boils down to having the proper consent. 

There are two types of consent:

  • Explicit (also sometimes referred to as express consent) 
  • Implicit (also sometimes referred to as implied or inferred consent) 

This information is not legal advice. Klaviyo recommends that you consult with your legal counsel to make sure that you comply with applicable laws in connection with your marketing activities. 

Explicit consent 

Explicit consent occurs when someone directly tells you that they want to receive marketing messages from your brand. You can get express consent when they: 

  • Sign up through a form
  • Give you their information on an in-person mailing list (in your store or at a booth)
  • Tell you verbally that they want to get marketing messages from you and provide you with their contact information

With explicit consent, the subscriber must knowingly consent to receive marketing messages. 

Pros and cons of explicit consent



Provides higher-quality subscribers

May lead to fewer subscribers

Is always allowed 

Doesn’t expire

Is required for SMS using Klaviyo

When you have express consent, you are free to send that subscriber marketing messages until they opt out — it doesn’t expire.

Express consent is required to send SMS messages using Klaviyo. For other marketing channels (e.g., email), it depends on the laws in a recipient’s country, and some require express consent. For instance, Canada’s Anti-Spam Legislation requires express consent for all commercial electronic messages except in specific circumstances. 

One con with express consent is that fewer people will explicitly opt in than implicitly opt in. Thus, list growth might be slower, but those who do subscribe will be higher-quality contacts than those who haven’t knowingly or explicitly consented. 

Implicit consent

Implicit consent is when someone gives you their contact information (e.g., email address, phone number, etc.) but does not explicitly say they want to receive marketing messages from your brand. A common example of implicit consent is when a customer makes a purchase and provides their email at checkout. They have not explicitly said they want to receive marketing messages from the brand, but it can be inferred that they have an interest in relevant content. In this case, you have their information, but they haven’t agreed to receive marketing communications. 

Examples of implied consent include: 

  • Signing up for gated content or resources (e.g., a forum, article, Wi-Fi network, etc.)
  • Inputting contact information during checkout (if they haven’t checked a box or otherwise agreed to receive marketing messages)
  • Giving you a business card
  • Buying or leasing a service, good, or product from you
  • Agreeing to a contract (written or electronic) with you
  • Partaking in a gaming or investment opportunity with you
  • Making a donation to you (if you are a registered charity or political organization)
  • Volunteering for you (if you are a registered charity or political organization)
  • Being a member of your organization’s club, association, or non-profit volunteer group

The laws around implied consent vary by country; typically when implied consent is allowed, it is either restricted to a certain time frame (e.g., it’s only good for two years) or in specific circumstances. 

Pros and cons of implicit consent



Provides a greater number of subscribers

Leads to low-quality subscribers and deliverability issues


Usually expires after a certain amount of time


Is banned or heavily restricted in certain jurisdictions


Is not allowed when using Klaviyo SMS 

A pro of implied consent is that you can gather a lot more contacts with implied consent than express consent. However, since these contacts haven’t actually agreed to receiving marketing messages from your brand, they are more likely to opt out or mark you as spam, leading to deliverability issues. If there are enough complaints, you can wind up on block-lists for email service providers (e.g., Gmail and Yahoo). 

Implied consent is not allowed in certain jurisdictions, and in others, it’s only allowed under special circumstances. Thus, by relying on implied consent, you risk running into compliance issues, depending on where your recipients are located.

Implied consent also expires and is not allowed when using Klaviyo SMS. 

Best practices for consent

There are a few best practices for consent you should follow:

  • Get express consent/avoid sending to those with implied consent
  • Make it clear what recipients are opting into 
  • Record the method of consent collection (i.e., when, where, and how someone gave express consent)
  • Use double opt-in 

We recommend getting express consent whenever possible. If you collect implied consent and it’s allowed in a jurisdiction you send to, use a separate list for those with implied consent. Furthermore, retarget these contacts to try to obtain their express consent, such as targeting them via social media or signup forms. 

Form targeting customers in a list or segment of email subscribers

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