How to Audit HubSpot Email Deliverability and Domain Health

When email performance starts declining, the first instinct is often to rewrite the copy.

Change the subject line. Shorten the email. Add more personalization. Test a different CTA.

But low opens, rising bounces, missing engagement data, or weak replies are not always messaging problems.

They can indicate a deeper HubSpot email deliverability issue involving the sending domain, email authentication, CRM data quality, tracking configuration, or the way marketing and sales outreach are structured.

That distinction matters before scaling.

If the underlying sending environment is weak, increasing volume simply exposes more contacts—and potentially your domain reputation—to the same problem.

A HubSpot email deliverability audit should therefore answer three questions before you launch larger campaigns:

1. Can HubSpot send reliably from the intended domain?
2. Are you sending to contacts who should actually receive the email?
3. Are you using the right type of outreach for that audience?

Here is how to audit all three.

Signs of a HubSpot Email Deliverability Problem

One underperforming campaign does not automatically mean you have a deliverability problem.

Look for patterns across multiple sends.

Common warning signs include:

• Hard bounces increasing over time
• An unusual spike in unsubscribes
• More spam complaints
• Opens or clicks suddenly falling after a domain or configuration change
• Emails showing as delivered but generating almost no engagement
• Sales representatives reporting that prospects never received messages
• One list performing substantially worse than others
• One sender or sending domain consistently underperforming
• Marketing email performance deteriorating as volume increases
• Tracking data appearing incomplete or inconsistent

HubSpot’s Email Health dashboard can help teams review metrics including open rate, click-through rate, unsubscribe rate, spam reports, and hard-bounce rate over time.

The important part is not to diagnose these metrics independently.

For example, low opens could indicate inbox placement issues—but they could also result from weak targeting or privacy features preventing open tracking.

A high bounce rate could point to sender reputation—but it could just as easily mean that a newly imported contact list contains old or invalid addresses.

The audit should identify where the failure begins.

Start Your HubSpot Domain Audit With the Sending Configuration

Before analyzing copy or audience behavior, confirm that HubSpot is sending from the domain you expect.

A HubSpot domain audit should document:

• Every domain and subdomain being used for email
• Which HubSpot emails use each domain
• Which addresses appear in the From field
• Which inboxes are connected for sales outreach
• Whether reply-to addresses are correct
• Whether marketing and sales emails use different sending paths
• Which additional platforms also send on behalf of your domain

This becomes particularly important in organizations with multiple brands or email tools.

A team might use HubSpot for marketing email, individual Google or Microsoft inboxes for sales communication, another platform for prospecting, and separate tools for recruiting or customer communication.

If that architecture is not documented, one configuration change can affect far more than a single campaign.

Confirm your HubSpot email sending domain

In HubSpot, review the domains configured under the email sending settings and confirm that the expected domain is authenticated and matches the address being used for marketing email.

HubSpot’s current domain-authentication process includes MX, DKIM, SPF, and DMARC configuration. HubSpot also displays whether an email sending domain is not authenticated, partially authenticated, or authenticated.

Do not assume the setup is correct because campaigns are technically being sent.

Test actual sends and verify:

• From address
• Reply-to address
• Sending domain
• Connected inbox
• Authentication status
• Email type

If the configuration recently changed, compare performance before and after the change.

Check Email Authentication and Domain Health

Email domain health depends partly on whether receiving mail systems can verify that your messages are legitimate.

Three authentication standards are particularly important.

SPF

SPF helps verify which systems are authorized to send email on behalf of your domain.

If several tools send email for your organization, the SPF configuration needs to account for the legitimate senders without creating conflicting records.

DKIM

DKIM adds a cryptographic signature that allows the recipient’s mail server to verify the message.

HubSpot notes that emails sent without appropriate DKIM authentication are more likely to bounce, be quarantined, or be classified as spam.

DMARC

DMARC provides instructions for how receiving systems should handle messages that fail authentication and helps protect the domain against impersonation.

A complete audit should therefore verify:

• DKIM status
• SPF configuration
• DMARC configuration
• Domain alignment
• Whether other sending tools have been considered
• Whether any recent DNS changes affected HubSpot

Authentication alone will not guarantee inbox placement. But it removes a fundamental infrastructure problem before you start diagnosing audience or content performance.

Review HubSpot Bounce Rate by Segment, Not Just Overall

A rising HubSpot bounce rate deserves investigation before additional outreach is launched.

But an account-wide percentage alone is not enough.

Break bounce performance down by:

• Contact source
• Import
• Campaign
• List
• Sender
• Domain
• Audience type
• Date added to the CRM

Suppose your established nurture audience continues performing normally while contacts from one recently uploaded list generate significantly more hard bounces.

That suggests the primary problem is likely the data source, not the entire email infrastructure.

Distinguish hard and temporary delivery problems

Hard bounces generally indicate that the email cannot be delivered permanently—for example, because the address is invalid or no longer exists.

Temporary delivery failures require a different diagnosis.

The key operational rule is that known bad addresses should not continue circulating between campaigns.

HubSpot records recipient-level bounce events, and contacts that bounce, unsubscribe, or submit spam reports are prevented from receiving subsequent marketing emails under relevant conditions.

Your audit should still determine why those records entered the send in the first place.

Otherwise, every new campaign becomes another contact-cleanup exercise.

Audit CRM Hygiene Before Blaming the Email

Deliverability and CRM quality are closely connected.

Before scaling HubSpot email outreach, review whether the audience contains:

• Old contacts
• Duplicate contacts
• Hard-bounced addresses
• Contacts with unclear acquisition sources
• People outside the intended buyer profile
• Former employees
• Personal email addresses where business addresses are expected
• Job seekers mixed with business prospects
• Long-term unengaged contacts
• Contacts whose subscription or communication status is unclear

A CRM with 30,000 contacts does not automatically provide an audience of 30,000 people who should receive the next campaign. Using HubSpot lead qualification and scoring can help separate genuinely relevant contacts from records that should remain excluded or in nurture.

HubSpot recommends organizing contacts around why they expressed interest and using engagement and source information to keep sending audiences relevant.

This means CRM hygiene is not simply a database-administration task.

It directly affects your ability to run email programs confidently.

Diagnose HubSpot Email Tracking Issues Separately

Deliverability and tracking are related, but they are not the same problem.

A message may be delivered while the engagement data you see in HubSpot remains incomplete.

That is why HubSpot email tracking issues should have their own audit path.

How HubSpot open tracking works

HubSpot can register an email open when an embedded tracking pixel loads. If a recipient’s email client blocks images or uses privacy features that prevent the pixel from loading normally, open activity may not be recorded as expected.

Sales email tracking is subject to similar limitations, and privacy settings can also affect whether open activity is available. 

This makes open rate a useful signal—but not a perfect measurement of human attention.

Do not diagnose deliverability from opens alone

Suppose open rate drops.

Before concluding that emails are entering spam, compare:

• Delivered emails
• Bounces
• Clicks
• Replies
• Meetings
• Unsubscribes
• Spam reports
• Performance by recipient domain
• Performance by sender

HubSpot also filters suspected bot activity from parts of its engagement reporting.

Your goal is to determine whether you have:

A delivery problem: Messages are being rejected.

An inbox-placement problem: Messages are technically delivered but not reaching useful inbox visibility.

A measurement problem: Engagement occurs but tracking cannot capture it reliably.

A targeting problem: Messages arrive but recipients do not care.

A messaging problem: The audience is relevant but the email does not generate action.

Those require different fixes.

Audit Marketing Email Consent and Audience Quality

Another common mistake is treating every HubSpot contact as interchangeable.

Someone who:

• Requested a resource
• Registered for a webinar
• Spoke with sales
• Became an existing customer
• Was imported from an older database
• Was sourced for prospecting

has a different relationship with your organization.

Your email strategy should reflect that.

Before a marketing send, establish:

• Why the person is in HubSpot
• What communication they expect
• Which subscription category applies
• Whether they meet your internal marketing eligibility criteria
• Whether applicable consent and privacy requirements have been addressed
• When they last engaged

The appropriate requirements depend on your audience and jurisdiction, so legal and compliance teams should define the rules relevant to your organization.

From a deliverability perspective, however, the principle remains consistent:

Sending more email to people who do not expect or value it is unlikely to improve domain health.

Separate HubSpot Marketing Emails From Sales Sequences

One of the most useful findings in an email audit may have nothing to do with DNS.

The outreach method itself may be wrong.

HubSpot marketing email is designed for one-to-many marketing communication such as:

• Newsletters
• Educational nurture
• Event promotion
• Product announcements
• Lifecycle campaigns

Rep-led sales communication serves a different purpose.

For appropriate sales follow-up, a sequence from an individual salesperson may make more sense than sending another message from a generic marketing alias.

This distinction became important during one of Xgrid’s broader HubSpot engagements.

Xgrid worked with a multi-brand staffing company whose marketing email performance was being affected by deliverability and tracking concerns. During the engagement, Xgrid identified a domain configuration issue affecting email tracking and expanded the investigation into a broader email-domain audit covering email performance, data quality, and CRM hygiene.

Instead of simply changing campaign copy, Xgrid recommended moving suitable sales follow-up away from broad marketing-style sends and toward more targeted, rep-led HubSpot sales sequences. The test used individual salesperson inboxes rather than a generic marketing alias and produced stronger engagement signals across opens, clicks, and replies. The client subsequently requested additional sequences for different segments.

That is the broader lesson:

Sometimes improving email performance requires changing the outreach architecture, not rewriting the email.

Do Not Use One Email System for Every Outreach Motion

Cold prospecting deserves another distinction.

A business may determine that HubSpot is the right system for:

• CRM management
• Marketing nurture
• Known-contact communication
• Sales follow-up
• Opportunity management

while using different infrastructure for larger-scale cold prospecting.

In the same Xgrid engagement, the team advised the company to use a more appropriate outbound platform for cold prospecting and provided guidance around domain setup, inbox infrastructure, warming, and protecting deliverability as outreach scaled.

That separation can prevent one outreach motion from unnecessarily affecting the communication channels used for existing customers, engaged leads, and active sales conversations.

It also makes each channel easier to monitor.

When to Pause a HubSpot Email Campaign

Sometimes the correct optimization is to stop sending temporarily.

Do not wait for every metric to deteriorate simultaneously.

Consider pausing or reducing sends when:

• Hard bounces increase unexpectedly
• Spam complaints appear above normal patterns
• An imported list performs substantially worse than established audiences
• A sending-domain configuration has changed unexpectedly
• Authentication cannot be verified
• A sender or domain suddenly experiences unusual failures
• Emails are going to an audience whose eligibility cannot be confirmed
• Tracking changes make campaign performance impossible to interpret
• A sequence continues sending after clear negative signals
• HubSpot stops a send because of negative engagement

HubSpot can automatically stop marketing email sends when it detects unusually high levels of hard bounces, spam reports, unsubscribes, or other risk indicators. Repeated stopped sends can contribute to more serious email-sending restrictions.

A pause is not a failure.

Continuing to send while you know something may be wrong is the greater risk.

Build a HubSpot Email Deliverability Remediation Plan

Once the audit identifies the likely causes, do not fix them independently.

Create a remediation plan in the right order.

1. Contain the immediate risk

Pause affected audiences, campaigns, senders, or sequences if necessary.

Do not continue increasing volume while investigating a clear negative pattern.

2. Fix the sending-domain configuration

Validate:

• Correct HubSpot sending domain
• Authentication
• From addresses
• Connected sales inboxes
• Reply-to configuration
• Other platforms authorized to send

Resolve infrastructure issues before testing campaign performance again.

3. Clean the CRM audience

Segment or suppress:

• Hard bounces
• Invalid records
• Duplicates
• Poor-fit contacts
• Long-term disengaged audiences
• Contacts with unclear communication status

Do not immediately replace a weak list with an even larger list.

4. Separate outreach types

Define which communications belong in:

• Marketing email
• HubSpot sales sequences
• Individual rep follow-up
• Dedicated cold-outbound infrastructure

The sending method should match the relationship with the recipient.

5. Restart with controlled segments

Test the repaired process on a smaller, high-quality audience.

Monitor:

• Delivery
• Hard bounces
• Spam reports
• Unsubscribes
• Clicks
• Replies
• Meetings or desired conversions

Then increase volume only if performance remains stable.

6. Monitor domain health continuously

Deliverability should not disappear from the team’s priorities once the campaign improves.

Create recurring reporting for:

• Hard-bounce rate
• Unsubscribe rate
• Spam reports
• Email health
• Performance by sender
• Performance by list source
• Performance by audience
• Sales-sequence replies

The objective is to identify deterioration early rather than waiting for another major audit.

A HubSpot Email Deliverability Audit Checklist

Before scaling your next outreach program, verify:

Sending infrastructure

• Correct sending domain
• SPF reviewed
• DKIM verified
• DMARC reviewed
• From and reply-to addresses confirmed
• Connected inboxes tested

CRM quality

• Hard bounces suppressed
• Duplicate contacts reviewed
• New imports validated
• Contact sources understood
• Poor-fit records excluded
• Long-term disengaged contacts reviewed

Tracking

• Open and click tracking settings reviewed
• Controlled test emails completed
• Performance compared across senders
• Privacy and bot-related measurement limitations understood

Audience

• Marketing eligibility is clear
• Subscription and consent rules are defined
• Content matches the audience’s relationship with the company
• Marketing and sales motions are separated appropriately

Scale readiness

• Bounce patterns are stable
• Complaints are being monitored
• Engagement is meaningful
• Sequence exit rules are defined
• A process exists for pausing problematic sends

If several of these cannot be confirmed, increasing email volume should not be the next step.

Frequently Asked Questions About HubSpot Email Deliverability

How do I improve HubSpot email deliverability?

Start with a HubSpot email deliverability audit covering domain authentication, sending configuration, bounce patterns, CRM data quality, audience eligibility, tracking, and sending behavior. Fix infrastructure and audience issues before increasing volume.

Why is my HubSpot bounce rate high?

A high HubSpot bounce rate can result from invalid or outdated email addresses, poor-quality imports, recipient-server rejection, authentication problems, or an audience that has not been properly maintained.

How do I check email domain health in HubSpot?

Review your connected email sending domains and authentication status, then monitor HubSpot’s Email Health metrics such as hard bounces, spam reports, unsubscribes, opens, and clicks.

Why are HubSpot email opens or clicks inaccurate?

Open tracking relies partly on a tracking pixel, so privacy features and image blocking can affect recorded opens. Bot filtering and security systems can also affect engagement measurement, so opens should not be evaluated alone.

When should I pause a HubSpot email campaign?

Pause and investigate when bounce rates or complaints rise unexpectedly, authentication fails, a new audience performs abnormally, or a domain or sending configuration issue makes continued outreach risky.

Fix HubSpot Email Deliverability Before You Scale

Poor email performance does not automatically mean you need better copy.

Sometimes the more important questions are:

Is HubSpot sending through the right infrastructure?

Can you trust the contact data?

Are engagement metrics being interpreted correctly?

Should this communication be a marketing email, a sales sequence, or a separate outbound motion?

A good HubSpot email deliverability audit answers those questions before additional volume magnifies the problem.

Xgrid helps B2B teams audit HubSpot email domains, diagnose tracking and deliverability issues, review CRM data quality, restructure marketing and sales outreach, and build more reliable HubSpot sequences and workflows.

If email performance is becoming harder to trust, Xgrid can audit the infrastructure behind your HubSpot outreach and identify what needs to change before you scale the next campaign.