Troubleshooting HubSpot email deliverability and reputation requires a systematic approach focusing on technical authentication, list hygiene, engagement optimization, and performance monitoring. HubSpot’s deliverability success depends heavily on sender reputation, which is influenced by factors like bounce rates, spam complaints, and recipient engagement. The most critical steps involve authenticating your domain (SPF, DKIM, DMARC), gradually warming up your sending volume, and maintaining a clean, engaged contact list. HubSpot provides built-in tools like the Email Health Dashboard to track metrics such as open rates (target: >27%), bounce rates (target: <0.3%), and spam complaints (target: <0.01%), which directly impact your domain’s reputation ^[6][8].

• Authentication is non-negotiable: Configure SPF, DKIM, and DMARC records to verify your sending domain and prevent spoofing. HubSpot offers an in-app wizard to simplify this process ^[5][4].
• List quality determines success: Invalid or unengaged contacts harm deliverability. Use third-party validation tools (e.g., Neverbounce, Kickbox) and suppress contacts with no engagement for over 6–12 months ^[2][7].
• Gradual warm-up protects reputation: New domains or IPs require a 30–60 day warm-up period, starting with small, highly engaged segments and slowly increasing volume ^[1][5].
• Monitor metrics relentlessly: The Email Health Dashboard provides real-time data on bounces, spam complaints, and engagement. Act on thresholds: suppress hard bounces (>0.3%) and investigate spam rates (>0.01%) immediately ^[6][8].

Step-by-Step Troubleshooting for HubSpot Deliverability

1. Authenticate Your Domain and Configure DNS

Domain authentication is the foundation of email deliverability, verifying your identity to inbox providers and reducing the risk of emails being marked as spam. HubSpot mandates SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) setup, which can be completed via HubSpot’s built-in wizard or manually through your DNS provider.

Without authentication, emails may fail DMARC checks, leading to rejection or spam folder placement. For example, a user in the HubSpot Community reported emails being blocked until SPF and DKIM were properly aligned ^[4]. HubSpot’s automated suppression of bounces and spam complaints further protects your reputation, but authentication ensures these mechanisms work effectively ^[5].

• SPF Record: Specifies which IP addresses are authorized to send emails on your domain’s behalf. HubSpot provides the exact SPF record to add: v=spf1 include:_spf.hubspot.com ~all ^[5].
• DKIM Record: Adds a digital signature to emails, verifying they haven’t been altered. HubSpot generates a unique DKIM key pair in the Settings > Domains & URLs section ^[1].
• DMARC Record: Instructs receiving servers on how to handle emails failing SPF/DKIM. Start with a "monitor-only" policy (p=none) to avoid blocking legitimate emails during testing ^[4].
• Allowlisting HubSpot IPs: Add HubSpot’s sending IPs to your allowlist to prevent corporate firewalls or security tools from blocking emails. The full list is available in HubSpot’s Deliverability Settings ^[3].

Common Pitfalls:

• Incorrect DNS syntax (e.g., missing semicolons or quotes) can break authentication. Use HubSpot’s Domain Connect tool to auto-validate records ^[10].
• DMARC alignment failures occur if the "From" domain doesn’t match the DKIM/SPF domain. Ensure consistency across all email headers ^[9].

2. Optimize List Hygiene and Engagement

Poor list quality is the leading cause of deliverability issues, directly impacting your domain reputation. HubSpot automatically suppresses hard bounces, unsubscribes, and spam complaints, but proactive list management is essential to maintain high engagement rates. A cumulative open rate below 10% triggers reputation risks, requiring immediate action ^[7].

Start by segmenting your list based on engagement. HubSpot’s Email Health Dashboard flags contacts with no opens or clicks in 6+ months—these should be suppressed or re-engaged separately ^[6]. For example, a repair plan might begin by emailing only contacts who clicked in the past 2 weeks, then gradually expand to less engaged segments over 8 weeks ^[7].

• Validation Tools: Integrate third-party services like Neverbounce or Kickbox to scrub lists for invalid, disposable, or role-based emails (e.g., info@, sales@) before importing to HubSpot ^[2].
• Double Opt-In: Enable double opt-in for all signup forms to ensure explicit consent and reduce spam complaints. HubSpot’s forms support this natively ^[3].
• Graymail Suppression: Use HubSpot’s graymail suppression feature to exclude contacts who haven’t engaged in 6–12 months. This prevents "zombie" contacts from dragging down metrics ^[1].
• Engagement Thresholds: Monitor these benchmarks:
• Open rate: >27% (industry average) ^[8]
• Click-through rate: >8% ^[8]
• Hard bounce rate: <0.3% ^[6]
• Spam complaint rate: <0.01% ^[8]

Actionable Repair Plan:

1. Week 1–2: Send only to contacts who clicked an email in the past 14 days.
2. Week 3–4: Expand to contacts who opened (but didn’t click) in the past 4 weeks.
3. Week 5–6: Include contacts who opened in the past 6 weeks.
4. Week 7+: Gradually reintroduce older segments if open rates remain stable (>20%) ^[7].

Avoid:

• Purchased or rented lists, which HubSpot explicitly prohibits. These lists often contain spam traps, leading to immediate reputation damage ^[5].
• Sending to contacts who haven’t engaged in over a year. HubSpot recommends suppressing these entirely ^[7].

3. Monitor and Diagnose with HubSpot’s Tools

HubSpot’s Email Health Dashboard and Deliverability Reports provide real-time insights into reputation risks. These tools track metrics like bounce rates, spam complaints, and inbox placement, allowing you to preemptively address issues. For example, a sudden spike in hard bounces (>0.5%) may indicate a compromised list or authentication failure ^[6].

• Email Health Dashboard: Located under Marketing > Email > Deliverability, this tool displays:
• Sender Score: A 0–100 rating (aim for >90) based on engagement and complaints ^[4].
• Bounce Categories: Distinguishes between hard (permanent) and soft (temporary) bounces. Investigate hard bounces immediately ^[3].
• Spam Feedback Loops: Shows which providers (e.g., Gmail, Outlook) are flagging your emails as spam ^[5].
• Google Postmaster Tools: Connect your domain to Google’s dashboard for Gmail-specific metrics, including spam rate and domain reputation ^[4].
• Sender Score by Return Path: Check your IP/domain reputation score (free via HubSpot’s integration) to benchmark against industry standards ^[9].

• Suppress contacts after 3 consecutive non-opens.
• Tag high-risk contacts (e.g., those marking emails as spam) for manual review ^[10].

4. Warm Up New Domains and IPs

New sending domains or dedicated IPs lack reputation history, making them vulnerable to spam filtering. HubSpot recommends a 40-day warm-up period for dedicated IPs, during which you gradually increase send volume while maintaining high engagement ^[5]. For shared IPs (used by most HubSpot customers), focus on list quality and authentication to leverage HubSpot’s existing reputation.

• Phase 1 (Days 1–10): Send to your most engaged segment (e.g., contacts who clicked in the past 30 days). Limit volume to 500–1,000 emails/day ^[1].
• Phase 2 (Days 11–30): Expand to contacts who opened in the past 60 days. Increase volume by 20% weekly ^[5].
• Phase 3 (Days 31–40): Introduce less engaged contacts (opened in past 90 days). Monitor bounce and spam rates closely ^[9].

Tools to Accelerate Warm-Up:

• Warmy.io: Simulates real user engagement (opens/clicks) to build reputation faster. Use cautiously to avoid artificial inflation of metrics ^[9].
• HubSpot’s Deliverability Support: Enterprise customers can request a dedicated IP warm-up plan with guided volume increases ^[5].