Scaling HubSpot Email: Deliverability Best Practices

When sending emails through HubSpot, success depends on one thing: deliverability - your ability to land emails in inboxes, not spam folders. Poor deliverability can hurt engagement, damage your sender reputation, and even block critical emails from reaching recipients.

Here’s what you need to know to improve email deliverability while scaling campaigns:

• Authentication is key: Set up SPF, DKIM, and DMARC to ensure your emails are trusted by servers.
• List hygiene matters: Regularly clean your email lists to remove outdated addresses and unengaged contacts.
• Avoid sudden volume spikes: Gradually increase email sends to build trust with providers like Gmail and Outlook.
• Use tools wisely: HubSpot's Email Health dashboard, graymail suppression, and dedicated IP add-ons help maintain performance.
• Content impacts deliverability: Avoid spammy subject lines, excessive links, and overly image-heavy designs.

Scaling your email campaigns safely requires a mix of technical setup, list management, and careful volume increases. HubSpot’s tools, combined with external solutions like Mailforge, can help you manage these challenges effectively.

Setting Up HubSpot for High Deliverability

Getting your emails into inboxes starts with a solid technical setup. At the heart of this are three key authentication protocols - SPF, DKIM, and DMARC. These protocols act as trust signals, letting email servers know your messages are authentic and secure. Without them, even the most well-designed email campaigns can end up in spam folders.

How to Configure SPF, DKIM, and DMARC Records

SPF (Sender Policy Framework) ensures only authorized services can send emails on behalf of your domain. To integrate this with HubSpot, you’ll need to add HubSpot to your existing SPF record as a TXT record in your DNS settings. Make sure all authorized senders are consolidated into a single SPF record to avoid errors like “too many DNS lookups.”

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to your emails, allowing receiving servers to confirm that the message hasn’t been altered. In HubSpot, go to Settings > Domains & URLs > Email Sending Domains to find the CNAME records you need to add to your DNS provider.

DMARC (Domain-based Message Authentication, Reporting & Conformance) tells email providers how to handle messages that fail SPF or DKIM checks. It’s essential for protecting your brand and building trust with email providers. Start with a monitoring policy (p=none) to gather reports, and then move to stricter policies like quarantine or reject as you gain confidence. For DMARC to work effectively, your "From" domain must align with the domain authenticated through SPF and DKIM.

"DMARC and email deliverability are directly related. Valimail has found that brands can see up to a 10% boost in email deliverability after successfully reaching DMARC enforcement."

• Allegrow

Using Subdomains to Protect Your Main Domain

Email providers like Gmail and Outlook evaluate your domain’s reputation based on factors like engagement rates, bounce rates, and spam complaints. If your marketing emails negatively impact that reputation, it can hurt all emails sent from your domain - including transactional or customer service emails.

"Mailbox providers judge your domain, not individual departments."

• Allegrow

To safeguard your main domain, consider using subdomains for high-volume campaigns. For example, you could use marketing.yourcompany.com or news.yourcompany.com. This way, if a subdomain encounters issues like high bounce rates or spam complaints, your primary domain’s reputation - and its critical communications - remain intact.

This strategy becomes particularly important as your email volume grows in HubSpot. By isolating risks to subdomains, you can keep your main domain’s reputation strong.

Automating DNS Setup with Mailforge

Setting up DNS records manually can be tricky - and it’s a common stumbling block. In fact, about 80% of companies fail to enforce DMARC due to the technical challenges involved. When managing multiple domains, the complexity only increases.

That’s where Mailforge comes in. This tool automates the entire DNS configuration process. By adding your domain to Mailforge, you can auto-generate and push SPF, DKIM, and DMARC records via API. It even verifies DNS propagation for you.

This automation doesn’t just save time - it can reduce costs by up to 46% compared to manual setups. For businesses managing multiple domains - whether for A/B testing, geographic segmentation, or isolating risks - Mailforge simplifies bulk DNS updates. Plus, it works seamlessly with HubSpot, letting you combine HubSpot’s CRM and engagement features with Mailforge’s technical infrastructure for scalable email outreach.

Building and Maintaining a Quality Email List

The strength of your sender reputation hinges on the quality of your email list. Even if your DNS setup is perfect, sending emails to invalid addresses or disengaged contacts can quickly damage your deliverability. With email lists decaying at a rate of 2.1% per month, regular upkeep is non-negotiable to maintain a healthy reputation.

Email List Verification and Cleaning

Start by eliminating purchased, rented, or leased contacts. These sources are often riddled with spam traps and invalid addresses, leading to hard bounces[5, 11]. Use reliable verification tools to screen new contacts for invalid, spam trap, or catch-all emails.

To block bots, use CAPTCHA on your forms. Implementing double opt-in is another effective step to confirm subscribers are genuine[4, 1]. This extra layer of confirmation improves both the quality of your list and overall engagement.

Set up a verification process by syncing results into a custom HubSpot field, such as "Risk Analysis." Then, use HubSpot Workflows to automatically suppress risky records. Re-verify active contact pools every 30–60 days, and always review dormant segments before launching re-engagement campaigns.

Managing Unengaged Contacts

Internet service providers (ISPs) like Gmail and Outlook assess your sender reputation based on how engaged your audience is. If your emails are consistently ignored, it sends a signal that your content isn’t resonating. Open rates below 15% are a warning sign that could result in your emails landing in spam folders.

HubSpot properties like "Last marketing email open date" and "Sends since last engagement" can help you identify and pause unresponsive contacts. Consider implementing a 90-day sunset policy, followed by re-engagement campaigns before suppressing inactive contacts permanently. If those efforts don’t work, try alternative outreach methods like social media or phone calls.

"Email deliverability is a feedback loop for whether you're sending the right content to the right contacts at the right time."

• HubSpot

To further reduce risks, use HubSpot’s graymail suppression feature. This tool automatically excludes contacts based on their "Sends since last engagement" property, ensuring you don’t repeatedly email those who never interact[4, 7].

Automating these processes can save time and ensure your list remains clean and effective.

Automating List Hygiene with HubSpot and Mailforge

Manually cleaning your email list isn’t scalable. Instead, use HubSpot workflows to automate key tasks, like changing a contact’s status to "non-marketing" when they unsubscribe or when a hard bounce is detected. HubSpot workflows can also segment contacts based on recent activity, keeping your list well-organized.

For those managing multiple outreach domains, tools like Mailforge simplify bulk operations. Mailforge not only automates DNS and authentication for outreach domains but also safeguards your primary sender reputation.

Scaling Safely: Warm-Up and Volume Management

A sudden surge in email volume can set off spam filters, especially with providers like Gmail and Outlook. These platforms need to see steady, positive engagement over time before they trust your emails enough to deliver them to inboxes. That’s why a gradual warm-up process is key - it helps establish your sender reputation as you expand your email campaigns.

Warming Up Domains and Mailboxes

When you start using a new domain or switch to a different email service provider, mailbox providers don’t immediately trust your sender identity. Without an established history, your emails are treated cautiously until you demonstrate reliability. For instance, HubSpot offers an automated 40-day warm-up period for customers using its dedicated IP add-on. However, if you’re on shared infrastructure, you’ll need to handle this process manually. A common method is to begin with 10–20 emails per day and gradually increase to 50–100 daily over a span of 2–3 weeks. During this period, prioritize sending emails to your most engaged contacts to build trust.

If you’re managing outreach across multiple domains, tools like Warmforge can simplify the warm-up process. It automates the steps, reducing manual work and minimizing the risk of errors.

Once your domains are warmed up, the next hurdle is managing volume growth effectively.

Gradually Increasing Campaign Volumes

After completing the warm-up phase, scaling up your email volume needs to be done carefully to avoid triggering spam filters. Abrupt increases in activity can raise red flags. Instead, aim to grow your send volumes by 10%–20% per week. To maintain a good sender score, keep individual mailboxes capped at 50 to 100 emails per day. And if your hard bounce rate climbs above 2%, pause the campaign and reevaluate your contact list.

Using Mailforge's Shared Infrastructure

Once you’ve warmed up and scaled gradually, Mailforge provides a reliable infrastructure to help manage deliverability challenges. Unlike HubSpot’s shared IP setup - where poor practices by other users can harm your deliverability - Mailforge offers a more controlled shared infrastructure tailored for outreach. With Mailforge, you can set up hundreds of domains and mailboxes in minutes, complete with automated DNS configuration and SSL/domain masking to safeguard your primary domain.

Mailforge also integrates seamlessly with platforms like HubSpot, allowing you to manage warm-up and scaling efforts efficiently. Its built-in connection with Warmforge helps ensure your sender reputation remains strong as your campaigns grow.

Optimizing Email Content for Deliverability and Engagement

The content of your emails plays a key role in determining whether they land in your recipient's inbox or get flagged as spam. Mailbox providers closely examine elements like subject lines and the number of links in your email. As HubSpot puts it: "Email deliverability is a feedback loop for whether you're sending the right content to the right contacts at the right time". Striking the right balance between design and clarity is essential for improving inbox placement.

Designing Emails for Better Inbox Placement

Emails that rely heavily on images often trigger spam filters, especially when they include little to no accompanying text. To avoid this, focus on a text-first design, using images as a complement rather than the main feature. Keep your paragraphs short - 1 to 3 lines - to make your content easy to scan, especially on mobile devices.

Subject lines are another critical factor. Avoid using clickbait, excessive capitalization, or overly aggressive language, as these can harm your deliverability. Tools like HubSpot's subject line analyzer can help you test your subject lines for clarity and relevance before sending.

Personalization and Smart Link Practices

Personalization is more than just adding a recipient's first name - it’s about delivering contextually relevant content. HubSpot's personalization tokens let you reference details like the recipient's role, company, or recent activity. This level of personalization not only boosts engagement but also signals to mailbox providers that your emails are relevant and welcome. In fact, 91% of users will unsubscribe if they feel the content doesn’t meet their needs.

When it comes to links, less is more. Keep your link density low by focusing on a single, clear call-to-action (CTA). This approach reduces the likelihood of your email being flagged as spam while also making it easier for recipients to take action. A clean, text-focused email with one primary link is both effective and actionable.

Ensuring Compliance with Email Regulations

In addition to design and personalization, meeting compliance requirements is critical for maintaining sender credibility. Every marketing email must include a visible unsubscribe link and a valid physical business address. HubSpot simplifies this by automatically adding unsubscribe links to its templates. You can manage your business address in the Email Settings under Office Location.

Make sure your "From" name and email address are clear and recognizable. Pairing these elements with proper email authentication protocols like SPF, DKIM, and DMARC further establishes your legitimacy. As Allegrow emphasizes, "Include a visible unsubscribe and a real physical address, signals mailbox providers expect from reputable senders".

Monitoring and Improving Deliverability Performance

Keeping an eye on your email performance is key to understanding whether your scaling efforts are boosting or damaging your sender reputation. HubSpot's Email Health Dashboard acts as a central tool for monitoring deliverability. As HubSpot employee Amna Muratagic puts it:

"Think of the Email Health Dashboard as your command center for email deliverability. It helps you understand how inbox providers, such as Gmail or Outlook, perceive your emails based on how recipients engage with them".

This dashboard lays the groundwork for tracking the key metrics discussed below.

Tracking Deliverability Metrics in HubSpot

HubSpot uses a 1–10 Email Health Score to measure your email performance based on 30-day engagement metrics. Here’s how the scores break down: a score of 9–10 is labeled "Excellent", 7–8 is "Good", and anything below 5 indicates serious issues. You can access this data under Marketing > Email > Health, but note that at least 400 emails must have been sent in the past 30 days for this feature to be available.

Key metrics to monitor include:

• Hard bounce rate: Should stay below 2%.
• Spam report rate: Aim for under 0.1%.
• Unsubscribe rate: Keep it below 0.3%.

HubSpot also tracks how long recipients engage with your emails, categorizing their interaction as "Read" (8+ seconds), "Skimmed" (2–8 seconds), or "Glanced" (less than 2 seconds). This breakdown doesn’t just show whether your emails are opened - it provides insight into how much attention your content is receiving.

Using Mailforge for Deliverability Insights

While HubSpot focuses on engagement metrics, Mailforge goes deeper by offering infrastructure-level insights to support deliverability on a larger scale. If you're managing campaigns across multiple domains, Mailforge’s bulk DNS management tools make it easy to monitor and update authentication records across your entire setup. This is a lifesaver when handling hundreds of domains, where manual checks would be overwhelming.

Mailforge also tracks domain performance, helping you identify which domains are thriving and which ones need closer attention. This allows for smarter domain rotation strategies as you scale your campaigns.

Fixing Common Deliverability Issues

When problems arise, HubSpot's Delivery tab provides detailed reasons for hard and soft bounces. If your bounce rates are high, consider enabling HubSpot's graymail suppression feature, which automatically excludes contacts who aren’t engaging with your emails. For blacklisted domains or low engagement, warming up new domains gradually is key. Tools like Warmforge’s AI-powered warm-up system can help you slowly increase sending volume over 30–60 days when introducing new domains.

High spam complaint rates can also be a red flag. Interestingly, 69% of email recipients mark messages as spam based purely on the subject line. Even small adjustments to your subject lines and messaging can make a noticeable difference in reducing complaints.

Conclusion: Scaling HubSpot Email with Confidence

Key Deliverability Practices Recap

Scaling email campaigns successfully hinges on three essential practices: solid technical authentication, consistent list hygiene, and careful volume management. Technical authentication, using protocols like SPF, DKIM, and DMARC, helps establish your legitimacy with mailbox providers. Meanwhile, keeping your contact lists clean is crucial. With B2B database data decaying at a rate of about 2.1% per month - or roughly 22.5% annually - regularly verifying and cleaning your lists is non-negotiable. HubSpot’s graymail suppression feature can automatically exclude unengaged contacts, and verifying new lists before importing them helps avoid hard bounces. Gradually increasing email volume is equally important, whether you're warming up a dedicated IP over 40 days or rolling out emails from new domains.

"Email deliverability is a feedback loop for whether you're sending the right content to the right contacts at the right time".

In other words, keeping tabs on your performance through HubSpot’s Email Health Dashboard is just as critical as setting everything up correctly in the first place.

How Mailforge and HubSpot Work Together

Once you’ve nailed the basics of email deliverability, combining HubSpot with Mailforge can take your campaigns to the next level. Together, these tools allow you to scale your email efforts while maintaining both deliverability and effectiveness.

HubSpot shines when it comes to managing permission-based, inbound email efforts and keeping your CRM organized. However, it’s not built for large-scale cold outreach. That’s where Mailforge steps in. While HubSpot focuses on warm engagement and record management, Mailforge handles the heavy-duty technical infrastructure. This includes automated DNS setup, domain rotation, and the ability to manage hundreds of domains in just minutes. By separating these functions, you shield your primary HubSpot domain from the risks associated with cold email campaigns.

The strategy is straightforward: use Mailforge for cold outreach and sync only the positive responses back into HubSpot. With Mailforge managing the technical complexities and HubSpot taking care of your engaged contacts, you can scale your email campaigns confidently and efficiently without jeopardizing deliverability.

FAQs

Why should I use subdomains for email campaigns?

Using subdomains for your email campaigns is a smart way to safeguard your main domain’s reputation while ensuring better deliverability as your email volume grows. By keeping different email streams - like marketing, transactional, or cold outreach - separate, you reduce the risk of issues like high bounce rates or spam complaints affecting your primary domain’s credibility with Internet Service Providers (ISPs).

Subdomains also bring a level of organization and control that’s hard to achieve otherwise. Each subdomain can have its own set of SPF, DKIM, and DMARC records, which simplifies troubleshooting deliverability problems and warming up new email streams. For instance, you can assign specific subdomains to different email purposes, such as news.yourcompany.com for newsletters or tx.yourcompany.com for transactional emails. This setup not only improves performance tracking but also reinforces your brand identity.

In short, subdomains allow you to scale your email campaigns more effectively, protect your sender reputation, and ensure your emails consistently land in inboxes where they belong.

How does Mailforge make DNS setup easier for better email deliverability?

Mailforge simplifies DNS configuration by automating the setup of key records like SPF, DKIM, and DMARC. Rather than manually updating TXT entries through your DNS provider, Mailforge takes care of it for you. With just one click or an API call, the necessary records are generated and applied.

This automation not only saves time but also ensures accuracy, even when handling large-scale operations across hundreds or thousands of domains. Mailforge integrates effortlessly with major DNS providers like Cloudflare and Route 53, verifying that records are correctly published to enhance email deliverability.

Why should you increase email volume gradually when scaling campaigns?

Gradually increasing the volume of your emails is key to preserving a solid sender reputation and steering clear of spam filters. If your email activity suddenly surges, it can raise red flags with Internet Service Providers (ISPs), which might result in deliverability problems.

Taking a steady, measured approach mirrors natural sending patterns that ISPs are more likely to trust. This also gives you the chance to keep an eye on important metrics like open rates, bounce rates, and spam complaints. Over time, this method not only helps your emails consistently land in inboxes but also strengthens your reputation as a reliable sender.

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