How to Build an AI Agent for Gmail and HubSpot

The workflow problem

Startups and mid-market companies using HubSpot as their CRM rely heavily on email as a primary sales channel. SDRs send outbound sequences, account executives negotiate through email threads, and customer success managers handle renewals and upsells through their inbox. HubSpot’s email tracking pixel tells you when an email was opened, but it does not tell you what happened next.

The core problem is that Gmail and HubSpot operate as parallel systems with superficial connections. HubSpot can track opens and clicks on emails sent through its platform, but many reps send emails directly from Gmail – especially personalized one-off messages, replies to inbound inquiries, and sensitive pricing negotiations. These Gmail-sent emails exist outside HubSpot’s tracking. The rep’s Gmail inbox contains the real conversation, while HubSpot contains a partial record supplemented by whatever the rep remembers to log.

Lead scoring suffers as a result. HubSpot scores leads based on website visits, form fills, and email engagement with marketing sequences. But it misses the most important engagement signal of all: the prospect is actively emailing your sales team. A prospect who has exchanged eight emails with your AE this week is clearly more engaged than one who opened a marketing email once, but HubSpot’s lead score does not reflect this because the Gmail conversations are not captured.

The gap between what is happening in Gmail and what HubSpot knows creates inaccurate lead scores, incomplete contact timelines, and a CRM that does not reflect reality.

Why an AI agent, not just automation

HubSpot offers a Gmail extension that lets reps log emails and track opens from their inbox. But it requires the rep to click “Log” on every email, and it captures only the bare facts – sender, recipient, subject, timestamp. It does not interpret the email content.

An AI agent reads and understands email conversations. It does not just log the fact that an email was sent – it extracts the substance. When a prospect emails asking for a comparison between your Professional and Enterprise tiers, the agent records this as a buying signal and updates the contact’s HubSpot record with context: “Prospect comparing pricing tiers – likely evaluating upgrade from Professional to Enterprise.” This information feeds into lead scoring, deal stage progression, and the sales team’s understanding of where the prospect stands.

The agent also identifies patterns across email threads that indicate deal momentum or stagnation. If a prospect who was responsive last week has gone silent, the agent notices and can trigger a re-engagement workflow in HubSpot or alert the rep. Conversely, if a prospect suddenly starts CCing their CFO and legal team, the agent recognizes this as a procurement signal and updates the deal stage.

This kind of behavioral analysis from email content is beyond what any sync tool or logging extension can provide. It requires understanding natural language, recognizing business context, and translating unstructured communication into structured CRM data.

How it works with ACP

The Agentic Control Plane connects to Gmail via Google OAuth and to HubSpot via HubSpot’s OAuth 2.0 flow, giving the agent scoped API access to both platforms.

On the Gmail side, the agent can read email messages and threads, search by query, access labels and folders, and read message metadata (headers, timestamps, recipients). On the HubSpot side, the agent can read and write contacts, companies, and deals. It can update contact properties, create engagements (email activity records), modify lead scores through custom property updates, enroll contacts in workflows, and create tasks.

You describe the agent’s behavior: “Track all emails between my Gmail inbox and contacts in HubSpot. Log each substantive email exchange as an engagement on the contact record. Analyze email content for buying signals and update lead scores accordingly. When a prospect mentions a competitor, pricing, or timeline, update the deal properties.”

Here is a practical example:

Gmail thread with carlos.m@strataventures.com (4 messages over 3 days):

Latest message from prospect: “Thanks for the demo yesterday. Really impressed with the workflow builder – it would save our ops team at least 10 hours a week. I’ve looped in our Head of IT (cc’d) because he’ll need to sign off on the security requirements before we can move forward. Quick question: do you offer annual billing with a discount? We’re looking at a January start date for a team of 25 users.”

Agent actions:

• Logged email engagement on HubSpot Contact Carlos Medina at Company Strata Ventures
• Updated Deal Strata Ventures - Professional:
  • Added note: “Positive demo feedback. Prospect quantified value at 10 hrs/week saved for ops team. Head of IT looped in for security review. Interested in annual billing discount. Team size: 25 users. Target start: January.”
  • Updated Deal Stage: Demo Completed to Decision Maker Brought In
  • Updated Deal Property “Team Size”: 25
  • Updated Deal Property “Billing Preference”: Annual
• Created new HubSpot Contact: Head of IT at Strata Ventures (from CC’d email address) and associated with the deal
• Updated Lead Score: +15 points (decision maker involvement, quantified value, specific timeline)
• Created Task: “Send Strata Ventures annual billing pricing for 25 users” – Due: Tomorrow – Owner: Rep

The agent turned a single email into six CRM updates that would have taken the rep five minutes to perform manually – if they remembered to do them all.

Governance and security

Email is a deeply personal and legally sensitive communication channel. An agent that reads Gmail content must operate within strict boundaries.

The Gmail OAuth connection uses the gmail.readonly scope by default, giving the agent read-only access. It cannot send emails, delete messages, modify labels, or alter the inbox in any way. If your workflow requires the agent to send follow-up reminders or responses, the gmail.send scope can be added, but this is a separate, explicitly approved permission.

HubSpot OAuth scopes are equally granular. The agent requests only the specific scopes needed: crm.objects.contacts.read and crm.objects.contacts.write for contact management, crm.objects.deals.read and crm.objects.deals.write for deal updates, and crm.objects.owners.read for assignee management. It does not receive access to marketing email sending, workflow creation, or portal settings unless those scopes are explicitly granted.

The ACP audit log records every Gmail message the agent reads and every HubSpot record it creates or modifies. Audit entries include the email message ID, the HubSpot record IDs affected, the specific properties changed, and the values before and after each update. This provides full traceability for GDPR data processing records and SOC 2 audit evidence.

Email filtering rules let you exclude certain communications from processing. Emails from internal domains, messages matching specific subject patterns (like “Out of Office” or “Unsubscribe”), and emails involving certain contacts can be excluded. This ensures the agent only processes relevant customer communications.

Personal emails are protected. The agent processes emails based on matching recipients to HubSpot contact records. Emails sent to or from addresses that do not exist in HubSpot are ignored by default, meaning personal correspondence is never read or processed.

Example use cases

• Automatic email engagement logging: Every substantive email exchange with a HubSpot contact is logged as an engagement on their record, creating a complete communication timeline without manual logging. The agent writes concise summaries rather than dumping raw email text.

• Buying signal detection: The agent identifies signals in email content – pricing questions, timeline mentions, decision maker introductions, competitive comparisons – and updates HubSpot contact properties and lead scores to reflect the prospect’s buying readiness.

• Deal property updates from email context: When prospects mention team sizes, preferred billing cycles, specific use cases, or implementation timelines in emails, the agent updates the corresponding deal properties in HubSpot automatically.

• New contact creation from CCs: When a prospect CCs a colleague (manager, IT lead, procurement contact) on an email thread, the agent creates a new HubSpot contact for that person and associates them with the deal, expanding the buying committee map.

• Engagement gap alerts: The agent monitors email cadence with active deals and flags contacts where communication has dropped off. It can enroll stale contacts in a HubSpot re-engagement workflow or create a task for the rep.

Getting started

Start tracking prospect emails intelligently in three steps.

1. Sign up at cloud.agenticcontrolplane.com. Free accounts include both Gmail and HubSpot connectors.

2. Connect your tools. Authorize Gmail (you approve read-only access to your inbox) and HubSpot (log in with admin credentials and approve the requested CRM scopes) from the Data Sources page.

3. Describe your agent. Tell it what to track: “Log all prospect emails as HubSpot engagements. Update lead scores when you detect buying signals. Create tasks for follow-ups mentioned in emails.” The agent starts processing your inbox immediately.