Marketing & Sales Automation Guides

HubSpot Salesforce Integration: How to Send HubSpot Emails to a Salesforce Custom Object

Configuring HubSpot to support specific industries can be straightforward, especially with HubSpot’s data model templates, which offer out-of-the-box options to configure HubSpot for industries like healthcare, real estate, and education. Where these templates quickly fall short is when integrating to other key platforms with their own custom objects, such as a HubSpot Salesforce Integration. As of Q1 2025, one big challenge remains: ensuring that custom objects from other platforms can integrate and function as seamlessly as standard ones, especially in regulated industries like health tech.

We recently tackled this exact challenge as part of a recent HubSpot-Salesforce integration. For a health tech client, we needed to sync a custom “person” object from Salesforce to HubSpot while enabling communication and email outreach.

Unfortunately, this isn’t just a health tech problem. Many enterprise businesses leverage custom objects in Salesforce. HubSpot made progress in improving this in 2024 when they released bi-directional syncing of custom objects in the HubSpot Salesforce integration. We expect to see continued improvements here since the limitations of custom objects continue to receive negative reviews in the marketplace.

But for now, since the problem clearly exists, let’s talk about how we solved it using HubSpot’s Custom Coded automation tools and third-party middleware (Mulesoft).

Syncing a Salesforce Custom Object to a Contact in HubSpot

This health tech company was using standard objects in Salesforce to store healthcare provider information and a separate custom object to store Patient Lead information. We configured Salesforce’s native integration with HubSpot to support the healthcare provider information sync for Leads, Contacts and Accounts to HubSpot’s Contacts and Companies, but the custom object sync required a different approach.  We couldn’t simply set up a mirrored Patient Lead custom object in HubSpot to sync via the Salesforce integration for two specific reasons:

1. Custom Objects in HubSpot should really only be utilized when absolutely necessary. Because the custom object in Salesforce shared similarities to a Salesforce Lead, it made the most sense to tie this back to a Contact in HubSpot.
2. Custom Objects in HubSpot lose out on all the marketing functionality that a Contact has and was required for this use case.

Because of this, we needed a way to sync this custom data to HubSpot’s contact records to ensure the client could communicate and send emails to these individuals, distinguishing between healthcare providers and patients.

Faced with this limitation, we explored several solutions before landing on an approach that leveraged middleware and flows to pass the data between platforms.

How to Send HubSpot Emails to a Salesforce Custom Object

Here’s how it worked:

• Mapping Custom Object Properties – We created a HubDB table that stored property mappings between Salesforce and HubSpot. This allowed us to dynamically reference properties directly within this table rather than modifying custom code, ensuring easier management and updating.
• Automating Data Sync with Workflows – We built custom workflows in HubSpot to fetch patient-specific properties from the HubDB table, ensuring smooth data handling.
• Optimizing Sync Efficiency – The workflows checked whether properties had been updated since the last sync. If changes were detected, the updated data was sent back through middleware for Salesforce updates.
• Ensuring Data Accuracy – We implemented a timestamping system to track sync success and trigger updates only when necessary, reducing unnecessary API calls and improving performance. A custom field helped us to distinguish patients from healthcare provider records, which allowed the native integration to only handle healthcare provider records, and the custom integration to handle patient records.
• Collaboration with the Client’s Team – While we handled the HubSpot workflows, the client’s internal team configured their middleware (MuleSoft) to facilitate the data transfer to Salesforce.

While MuleSoft offers the capability to subscribe to property changes directly, we opted to leverage HubSpot workflows to control the data passed to MuleSoft. Centralizing the business logic within HubSpot allowed us to maintain clearer visibility into the decision-making process driving data syncs. We streamlined MuleSoft’s role to handle the data transfer to Salesforce, reducing complexity within the middleware layer. This approach not only simplified debugging by consolidating logging and process flow within HubSpot but also made it easier to tweak sync criteria without requiring development changes in MuleSoft.

Our take?

For companies with unique CRM and marketing automation setups, leveraging middleware like MuleSoft or Zapier can be a smart way to save development resources and avoid risky manual workarounds. These tools are built to handle things like data flow, security, and scalability — helping your teams stay focused on strategy instead of patching integration gaps.

Solved: Sending Emails to a Custom Object

By structuring the integration around middleware and flows, we created a solution that allows the client to:

• Seamlessly sync patient data between Salesforce and HubSpot.
• See the custom object in Salesforce as a contact object in HubSpot, enabling email communication and outreach.
• Easily update field mappings without changing the underlying code.
• Ensure long-term scalability and minimal maintenance effort.

At the end of the day, integrations should make your business more efficient.

Key Takeaways for Your HubSpot Salesforce Integration

If your team is facing similar integration challenges, consider these best practices:

• Don’t let out-of-the-box stop you, explore an alternative solution and leverage a strategic partner.
• Utilize middleware like MuleSoft or Zapier to bridge platform limitations.
• Optimize workflows to only sync necessary updates, improving efficiency.
• Collaborate across teams to ensure seamless implementation.

And most importantly, don’t settle for workarounds. A CRM should work for you, not against you.

Overcoming CRM Integration Hurdles

Navigating complex CRM integrations requires strategic problem-solving. It is never really a “one-size-fits-all” solution. Start with a HubSpot Marketing Migration Pre-Launch Checklist so you identify the requirements and complexities before your project starts. Avoid the pitfalls and frustrations by understanding that these projects are challenging, but full of opportunity to propel your business and operations forward.