What is the best practice for gaining new customers from a partner using email?
Matthew Whittaker
Co-founder & CTO, Suped
Published 6 Jul 2025
Updated 16 Aug 2025
8 min read
Expanding your customer base through strategic partnerships can be highly effective, but leveraging a partner's email list requires careful consideration. The landscape of email marketing and data privacy has evolved significantly, making it crucial to adopt best practices to ensure both compliance and optimal deliverability.
The traditional approach of emailing users from a partner list with an implicit opt-out option is no longer recommended, and in many regions, it's explicitly against the law. This method, often referred to as 'negative consent', can lead to severe deliverability issues, damage your sender reputation, and result in legal penalties. My experience shows that prioritizing explicit consent is the bedrock of a successful email acquisition strategy.
Instead of focusing on how users can opt-out, the emphasis should shift entirely to how they can actively opt-in to receive communications from your brand. This proactive approach builds a healthier, more engaged email list from the start, which is vital for long-term email marketing success and avoiding common pitfalls like being placed on a blocklist (or blacklist).
Understanding and implementing proper consent mechanisms is the first and most critical step when integrating new customers from a partner. It protects your brand and ensures your emails reach the inbox of genuinely interested recipients.
Prioritizing explicit consent
The cornerstone of ethical and effective email marketing, especially when working with partner lists, is explicit consent. This means recipients must clearly and unambiguously agree to receive emails from your company. Relying on an opt-out mechanism for lists provided by partners poses significant risks to your email deliverability and overall sender reputation.
From a legal standpoint, regulations like GDPR in Europe and CASL in Canada mandate explicit consent. Even in regions with less stringent laws, such as the United States under CAN-SPAM, the spirit of responsible email marketing leans heavily towards permission-based sending. Sending to individuals who have not explicitly agreed to receive your emails can lead to high complaint rates, spam trap hits, and ultimately, your domain or IP address being added to a blocklist.
To mitigate these risks, your partner should be responsible for obtaining explicit consent for you to market to their audience. This can be achieved through a co-branded signup form, a dedicated opt-in email sent by the partner, or a clear disclosure during their signup process that allows users to specifically agree to receive communications from your company. This ensures that every new subscriber on your list has a demonstrable interest in your content. You can learn more about how consent and incentives should be handled for referral emails.
Opt-out approach
Risk of complaints: Many recipients will mark your unsolicited emails as spam, damaging your sender reputation.
Spam traps: Acquired lists often contain dormant or recycled addresses that become spam traps, leading to blacklisting.
Legal non-compliance: Violates privacy laws in many jurisdictions, leading to fines.
Poor engagement: Recipients who didn't ask for your emails are less likely to open or click.
Furthermore, if you are planning to leverage an existing email list for a new sub-company, consent becomes even more critical. Each brand must ensure it has independent, verifiable consent for direct marketing communications. This dual consent ensures transparency and protects your brand's reputation.
Managing sender reputation and domains
When acquiring new customers via a partner, the domain from which you send your initial emails is pivotal. Sending from a completely new or un-warmed domain can immediately trigger spam filters, regardless of content, due to a lack of established sender reputation. It's often better to send from an already established domain with a good sending history.
The key here is to control your own sending infrastructure or at least ensure your partner's sending practices align with your deliverability goals. If you're using a new domain or an existing one for a new type of outreach, a proper email list warm-up process is indispensable. This gradually builds trust with mailbox providers and helps establish a positive IP and domain reputation.
Avoid sending from generic domains or shared IPs if possible, as they can have mixed reputations. Maintaining a strong sender reputation through consistent authentication (SPF, DKIM, DMARC) and positive engagement signals is crucial for getting into the inbox, especially when engaging new prospects. For B2B audiences, this is particularly important to improve B2B email deliverability.
Partner-managed sending (not recommended)
Lack of control: You have limited oversight on send volumes, frequency, and content quality.
Reputation risk: Partner's sending practices can negatively impact your brand's reputation.
Attribution issues: Difficult to track engagement and conversion for your specific offering.
Own domain sending (best practice)
Full control: Manage all aspects of your email campaigns, from volume to content.
Dedicated reputation: Build and protect your own sender reputation with consistent practices.
Accurate tracking: Gain precise insights into campaign performance and ROI.
Consider your existing sender email addresses and if they align with the new customer acquisition strategy. Consistency is key in how your emails appear to recipients and mailbox providers.
Crafting compelling initial emails
Once you have the explicit consent of potential customers from your partner's audience, the next step is to craft emails that resonate. The first email is critical for setting the tone and reinforcing the value proposition. It should clearly state why they are receiving the email, how their data was acquired (through the partnership), and what value you offer.
Personalization goes beyond just using their first name. Leverage any available data from the partnership to tailor content that speaks directly to their needs or interests. Focus on providing immediate value, whether it's an exclusive offer, helpful content, or an invitation to a relevant webinar. The goal is to build a relationship, not just make a sale.Email marketing best practices suggest that relevant, high-quality content leads to better engagement.
Your call to action (CTA) in these initial emails should be clear and concise, guiding the recipient to the next logical step, such as exploring your website, downloading a resource, or signing up for a deeper engagement. Avoid overwhelming them with too many options. This initial interaction is about nurturing, not aggressive selling. Consistent communication helps maintain client relationships.
Example: Opt-in confirmation email structure
Subject: A special offer from [Your Company Name] & [Partner Company Name]
Hi [First Name],
We're excited to connect with you! As a valued [Partner Company Name] customer, we thought you'd be interested in [Your Company's Product/Service] and how it can help you [benefit 1] and [benefit 2].
[Partner Company Name] has partnered with us to bring you [specific value proposition or exclusive offer].
Ready to learn more?
[Call to Action Button: Explore Our Offer / Learn More]
We look forward to helping you!
Sincerely,
[Your Name/Company Name]
P.S. If you'd prefer not to receive these updates, you can [Unsubscribe Link].
Remember to segment these new leads based on the partner source or any other relevant demographic information. This allows for more targeted follow-up campaigns and a better overall user experience, leading to higher open rates and improved email click rates.
Monitoring and optimizing for deliverability
Even with perfect consent and carefully crafted emails, continuous monitoring and optimization are essential for long-term success. Pay close attention to your email metrics, including open rates, click-through rates, bounce rates, and crucially, complaint rates and unsubscribe rates.
High complaint rates are a red flag that your emails are perceived as spam, even by those who opted in, potentially leading to your domain or IP being put on an email blacklist (or blocklist). Regularly checking your sender reputation through tools like Google Postmaster Tools is a non-negotiable step. Also, ensure your blocklist monitoring is active to quickly detect and address any listing issues. You can even check your status using a blocklist checker.
Regular list hygiene is equally important. Remove inactive subscribers and hard bounces to maintain a clean and responsive list. This proactive management helps improve your deliverability rates and reduces the risk of hitting spam traps. If you need to re-engage segments of your list that have become inactive, make sure you follow best practices for re-engagement safely.
Metric
Impact on deliverability
Action to take
Open rate
Indicates interest; low rates can signal content or subject line issues.
Test subject lines and preheaders; improve list segmentation.
By proactively monitoring these metrics and adjusting your strategy, you can maintain a healthy email program and maximize your customer acquisition efforts through partnerships. Regular assessment is crucial to improving your overall email deliverability.
Views from the trenches
Best practices
Always obtain explicit, verifiable consent from partner-sourced leads before adding them to your mailing list.
Ensure clear disclosure of the partnership and how the recipient's email was obtained in the first communication.
Segment partner lists for targeted, personalized content to improve engagement and relevance.
Implement a gradual warm-up process for any new sending domains or significant increases in volume.
Common pitfalls
Using an implicit opt-out method, which can lead to high spam complaints and blocklist issues.
Assuming partner consent transfers directly without your own explicit confirmation process.
Sending from a new, unwarmed domain without proper reputation building.
Neglecting to monitor key email metrics like complaint rates and bounce rates.
Expert tips
Set up robust email authentication (SPF, DKIM, DMARC) for your sending domains.
Regularly clean your email lists to remove inactive subscribers and hard bounces.
Use A/B testing for subject lines and calls to action to optimize engagement.
Provide immediate value in your first email to encourage positive interaction.
Expert view
Expert from Email Geeks says that relying on opt-out for partner lists significantly increases the risk of emails being blocked as spam.
2022-07-26 - Email Geeks
Expert view
Expert from Email Geeks says that explicit opt-in is crucial because opt-out methods often fail to capture recipients who haven't read the email or whose emails are directed to spam, including spam traps.
2022-07-26 - Email Geeks
Building lasting customer relationships through partner emails
Gaining new customers from a partner using email is a powerful growth strategy, but it hinges on adherence to best practices that prioritize consent, sender reputation, and recipient engagement. Moving away from outdated opt-out methods towards explicit opt-in ensures compliance and builds a foundation for healthy, long-term customer relationships.
By meticulously managing your sending domains, crafting personalized and valuable introductory emails, and continuously monitoring your email performance metrics, you can transform partner-sourced leads into loyal customers while safeguarding your email deliverability. Remember, every email sent should reinforce trust and provide clear value, ensuring your messages land in the inbox, not the spam folder.
