What tools and tips can improve email deliverability for a B2C onboarding flow with many Gmail addresses?
Michael Ko
Co-founder & CEO, Suped
Published 5 Jun 2025
Updated 17 Aug 2025
8 min read
Delivering an effective B2C onboarding flow is crucial for user retention and success, but it presents unique challenges, especially when a significant portion of your audience uses Gmail. My primary goal is to ensure these critical onboarding emails land in the primary inbox, not the promotions tab or, worse, the spam folder. Achieving high email deliverability means more users complete their onboarding journey, leading to higher activation rates and long-term engagement.
The sheer volume of emails in B2C onboarding, combined with Gmail's sophisticated filtering, demands a strategic approach. It is not just about sending emails; it is about sending them effectively so they are seen and acted upon. This involves leveraging the right tools for monitoring and testing, alongside implementing proven deliverability best practices for content and sender reputation.
Navigating Gmail's ecosystem requires understanding its algorithms and user engagement signals. My focus here is to provide practical advice and insights to help you optimize your B2C onboarding email flow, ensuring your messages consistently reach the inbox and drive the desired user behavior.
Implementing essential authentication protocols
A robust sender foundation is non-negotiable for improving email deliverability, especially with major inbox providers like Gmail. Implementing authentication protocols like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) is the first critical step. These protocols verify that your emails are legitimate and originate from authorized senders, significantly reducing the likelihood of them being flagged as spam. Gmail and Yahoo's new requirements for bulk senders, in particular, emphasize the mandatory use of these authentication standards.
DMARC goes a step further by providing instructions to recipient servers on how to handle emails that fail SPF or DKIM authentication. It also provides valuable reports that give you visibility into who is sending email on behalf of your domain. This allows you to identify and fix any unauthorized sending or misconfigurations. Properly configured authentication protocols are fundamental for email deliverability.
Your sender reputation is a critical factor, essentially a trustworthiness score assigned by internet service providers (ISPs). This score is influenced by various elements, including your email authentication, spam complaint rates, bounce rates, and engagement metrics. A strong reputation, bolstered by proper authentication, signals to ISPs that you are a legitimate sender, which is vital for improving Gmail deliverability. Utilizing tools like Google Postmaster Tools allows you to monitor your reputation directly with Google, providing insights into your sender score, spam rate, and delivery errors.
Crafting engaging content and managing engagement
The content of your onboarding emails significantly impacts how Gmail's algorithms classify your messages. For B2C flows, the goal is often to establish a personal connection and guide the user, making the email feel less like a marketing promotion and more like a helpful communication. This involves crafting clear, concise, and personalized subject lines and body copy. Avoid overly promotional language, excessive images, or too many links, as these can trigger spam filters and push your emails to the promotions tab. Maintain a healthy image-to-text ratio, ideally leaning more towards text.
Engagement is paramount for improving email deliverability with positive engagements. Gmail heavily prioritizes user interaction when determining inbox placement. Opens, clicks, replies, and adding your email to contacts all send strong positive signals. Conversely, marking emails as spam, deleting without opening, or not interacting at all can harm your sender reputation. While some email marketing experts suggest that the promotions tab is the inbox for some campaigns, for onboarding, direct inbox placement is generally preferred for immediate user action.
Good practices
Personalization: Use recipient names and tailor content to their specific actions.
Clear subject lines: State the email's purpose clearly and concisely.
Value-driven content: Focus on guiding the user and providing immediate utility.
Plain text ratio: Favor text over excessive images or rich media.
One-click unsubscribe: Provide an easy way for users to opt out, reducing spam complaints.
Bad practices
Generic content: Sending unpersonalized or irrelevant messages to all users.
Spam trigger words: Using phrases commonly associated with spam (e.g., 'free money').
Image-heavy emails: Emails consisting almost entirely of images with little text.
Missing unsubscribe link: Making it difficult for users to opt out, leading to spam complaints.
Negative engagement signals, such as high bounce rates or spam complaints, are clear indicators of deliverability issues. Gmail and other ISPs track these closely. A surge in complaints can quickly land your domain on a blacklist (or blocklist), severely impacting future email delivery. It is crucial to monitor these metrics continuously and address any increases promptly. Ensure you adhere to a strong email deliverability strategy.
Proactive monitoring and list health
Continuous monitoring of your email performance is fundamental. Key metrics to watch include bounce rate, complaint rate, and inbox placement rate. A high bounce rate, particularly from Gmail addresses, can indicate problems with list quality or domain reputation. Complaint rates are even more critical, as they directly impact your sender score. Regularly checking your inbox placement across various ISPs, especially Gmail, is essential to ensure your onboarding emails are not ending up in spam or promotional folders.
Importance of email validation
Implementing an email validation tool during the sign-up process for your B2C flow is a proactive measure. This helps prevent invalid, fake, or disposable email addresses from entering your list, which can lead to hard bounces and lower your sender reputation. It also helps in reducing fake sign-ups for welcome series emails.
Regularly check email blocklists (also known as blacklists) to ensure your sending IP or domain is not listed. Getting on a blocklist can severely disrupt your email delivery. If you find yourself on a blacklist, take immediate steps to identify the cause, fix the underlying issue, and request delisting. Proactive monitoring helps you catch issues before they escalate.
Maintaining a clean and engaged email list is vital. Regularly prune inactive or unengaged subscribers. Sending to unengaged addresses can lead to them becoming spam traps, which can further damage your sender reputation and lead to your emails going to spam. Focus your sending on subscribers who consistently interact with your emails, as this sends positive signals to ISPs.
Streamlining your onboarding email sequence
The onboarding email sequence itself needs careful consideration. For B2C, this often means a series of interconnected emails designed to guide new users through their initial experience. The frequency and timing of these emails are crucial. Avoid overwhelming new users with too many emails too quickly, as this can lead to unsubscribes or spam complaints. Instead, map out a logical flow that delivers value at each step, matching the user's journey. Experiment with different sending cadences to find what works best for your audience and onboarding goals.
Metric
Why it matters
Target for B2C Onboarding
Inbox placement rate
Directly indicates how many emails reach the primary inbox versus spam or promotions. Crucial for user activation.
Shows how engaging your subject lines are and initial user interest. Influences sender reputation positively.
Higher than marketing emails. Varies by industry.
Click-through rate (CTR)
Measures how effectively your content drives action, directly contributing to positive engagement signals.
Should be high given the transactional nature of onboarding.
Spam complaint rate
A critical negative signal. High rates lead to blacklisting and poor deliverability. Monitor with DMARC monitoring.
Below 0.1%. Google and Yahoo require below 0.3%.
Bounce rate
Indicates invalid or non-existent email addresses. High rates signal poor list hygiene.
Keep below 2%, ideally below 1%.
Each email in your onboarding flow should have a clear, single call to action (CTA). Overloading users with too many options can lead to decision paralysis and lower engagement. Also, consider leveraging user behavior data to segment your audience and send behavior-based emails. For example, if a user completes a specific step in your product, trigger an email congratulating them and guiding them to the next relevant action. This targeted approach significantly improves relevance and engagement, helping to avoid emails going to spam.
Views from the trenches
Best practices
Maintain a consistent sending volume and schedule to build a predictable sender reputation.
Segment your onboarding flows based on user behavior and demographics for higher relevance.
Regularly clean your email list by removing inactive subscribers and managing bounces effectively.
Ensure all transactional and onboarding emails are clearly differentiated from marketing content.
Common pitfalls
Sending high volumes of emails to unengaged or invalid Gmail addresses, hurting sender reputation.
Overly promotional content in onboarding emails, leading to placement in the promotions tab or spam.
Ignoring DMARC reports, missing critical insights into authentication failures and potential spoofing.
Failing to implement a one-click unsubscribe, which increases spam complaints and negative signals.
Expert tips
Focus on driving initial user engagement, such as logins or first actions, as this builds a positive sending history.
Prioritize email authentication (SPF, DKIM, DMARC) as the absolute foundation for trust with ISPs.
Actively encourage users to add your sending address to their contacts list to bypass filters.
For B2C, consider the emotional tone and value proposition in onboarding emails to foster connection, not just conversion.
Expert view
Expert from Email Geeks says inbox testing tools often test global filters applied when Google lacks specific sender/recipient information, missing personalized filters based on past interactions.
December 5, 2024 - Email Geeks
Expert view
Expert from Email Geeks says if there were clear rules to get mail out of the promotions tab, they would have been discovered. Google likely uses natural language processing to identify promotional content.
November 27, 2024 - Email Geeks
Final thoughts on optimizing B2C onboarding deliverability
Improving email deliverability for a B2C onboarding flow with a large Gmail audience requires a multi-faceted approach. It starts with solid technical foundations, ensuring your email authentication protocols are correctly set up and maintained. Beyond the technical, focusing on user engagement through relevant, personalized, and value-driven content is key. Proactive monitoring of your deliverability metrics, coupled with rigorous list hygiene, will help identify and mitigate issues before they impact your sender reputation.
By adopting these tools and tips, you can significantly enhance your chances of landing in the primary inbox, ensuring your crucial onboarding messages are seen and acted upon. This leads to higher user activation, better retention, and ultimately, a more successful B2C operation. Remember, deliverability is an ongoing process that requires continuous attention and adaptation to ISP guidelines and user behavior.
Gmail. Implementing authentication protocols like SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance) is the first critical step. These protocols verify that your emails are legitimate and originate from authorized senders, significantly reducing the likelihood of them being flagged as spam. Gmail and Yahoo's new requirements for bulk senders, in particular, emphasize the mandatory use of these authentication standards.
