How to Build an AI Agent for HubSpot and Gmail

The workflow problem

Sales reps send emails from Gmail. Marketing runs nurture campaigns from HubSpot. And the two systems fight over who owns the customer communication timeline. A rep sends a personal email from Gmail to a prospect. HubSpot does not know about it. The next day, HubSpot’s automated nurture sequence sends the same prospect a generic marketing email, undermining the personal relationship the rep just built.

On the other side, a prospect clicks a link in a HubSpot marketing email – a strong buying signal. The engagement data sits in HubSpot’s analytics dashboard, but the rep who owns the account is working in Gmail and never sees it. They do not know the prospect just spent twelve minutes reading the pricing page after clicking through from the email. They find out three days later during a CRM review, and by then the buying window has narrowed.

Manual email logging makes this worse. Reps are asked to BCC a HubSpot tracking address on every email, or use HubSpot’s Chrome extension to log emails. Compliance is inconsistent. Some reps forget. Others intentionally skip it for sensitive conversations. The CRM record becomes an unreliable patchwork: some emails logged, some not, engagement data incomplete, and the timeline full of gaps.

The outcome is a revenue team operating on partial information. Marketing sends emails that conflict with sales outreach. Sales misses engagement signals that would sharpen their timing. And CRM data is never complete enough to trust for forecasting or analysis.

Why an AI agent, not just automation

HubSpot already offers Gmail integration through its Chrome extension and email tracking pixels. But these tools are passive and mechanical. They log emails and track opens – they do not interpret what the engagement means or decide what should happen next.

An AI agent closes the interpretation gap. When a prospect opens a sales email three times in one hour and then clicks through to the case studies page, the agent does not just log those events. It recognizes a pattern: the prospect is building an internal business case. The agent alerts the rep with context: “Sarah at Acme opened your proposal email 3 times today and visited the case studies page twice. This pattern matches 73% of prospects who requested a reference call within 48 hours. Consider proactively offering one.”

For nurture sequences, the agent adds intelligence to what is normally a rigid, time-based automation. Instead of “send email 2 five days after email 1,” the agent adjusts based on behavior. If a prospect opened email 1 within minutes and clicked every link, the agent accelerates the sequence because interest is high. If a prospect has not opened any of the last three emails, the agent pauses the sequence and suggests a different channel (phone call, LinkedIn message) rather than continuing to fill an ignored inbox.

The agent also manages the coordination problem between sales and marketing emails. When a rep sends a personal email to a prospect, the agent detects it and automatically pauses the HubSpot nurture sequence to avoid a conflicting marketing touch. When the rep’s conversation concludes, the agent resumes nurture or adjusts the sequence based on the conversation outcome.

How it works with ACP

ACP connects to Gmail via Google OAuth 2.0 (Gmail API) and to HubSpot via OAuth 2.0. The agent operates as an intelligent middleware that keeps both platforms synchronized and adds behavioral interpretation.

Gmail tools available: Read emails (subject, body, sender, recipients, timestamps). Search emails with Gmail search syntax. Read email threads for conversation context. Send emails and replies. Read labels and categories. Access email metadata (open tracking via HubSpot pixel correlation, not native Gmail tracking).

HubSpot tools available: Read and update contacts, companies, and deals. Read email engagement data (opens, clicks, replies, bounces). Manage marketing email sequences and workflows. Create timeline events and notes on contact records. Read and modify lead scores. Enroll and unenroll contacts from sequences. Read email templates.

The agent continuously monitors both platforms and maintains a unified communication timeline. It logs Gmail emails to the correct HubSpot contact, enriches contact records with engagement insights, and adjusts nurture automation based on real-time behavior.

Here is a realistic workflow scenario:

Monday 9:30 AM – Agent processes overnight Gmail activity:

“3 contacts with significant overnight email engagement:

1. David Park (Cloudify Inc.) – Opened your proposal email at 11:47 PM and again at 6:12 AM. Clicked the pricing link both times. HubSpot lead score increased from 42 to 67. This prospect is actively evaluating pricing. Recommend sending a personalized follow-up this morning referencing the specific plan tiers they viewed.

2. Rachel Torres (DataBridge) – Replied to your check-in email at 7:45 AM: ‘Thanks for following up. We’re in the middle of budget planning and this is on our list. Can you send over a comparison with [Competitor]?’ I’ve paused the HubSpot nurture sequence for Rachel to avoid a conflicting automated email. I’ve also noted the competitor mention on her HubSpot record. Want me to draft a reply with the competitive comparison?

3. Mark Jensen (LogiFlow) – No engagement with the last 4 emails (sent over 3 weeks). HubSpot sequence has 2 more emails queued. Recommend pausing the email sequence. Mark may have gone dark. Consider a different channel: his LinkedIn shows he posted about attending an industry conference next week.”

Rep responds in Slack: “Pause Mark’s sequence and draft the competitor comparison for Rachel.”

Agent: “Done. HubSpot sequence paused for Mark Jensen. I’ve drafted a reply to Rachel with the competitive comparison based on the battlecard in HubSpot. Here is the draft for your review: [draft]. Send it from Gmail or should I adjust anything?”

Governance and security

Email data is among the most sensitive information in any organization. Connecting Gmail and HubSpot requires strict controls to prevent unauthorized access and ensure privacy compliance.

Gmail OAuth scopes: The agent requests gmail.readonly for reading emails and gmail.send for sending on behalf of the authenticated user. It does not request gmail.modify (which would allow deleting or labeling), and it cannot access emails of other users in the organization. Each user authenticates independently, so the agent only accesses the inbox of the user who connected it.

HubSpot OAuth scopes: The agent requests crm.objects.contacts.read and crm.objects.contacts.write for managing contact records, content for email template access, and automation for sequence management. It does not request access to financial objects (quotes, invoices, payments).

Email content handling: The agent reads email content in-memory to extract engagement signals and conversation summaries. It does not store raw email content in ACP infrastructure. Summaries written to HubSpot contact timelines are concise and do not include full email bodies unless explicitly configured.

Personal email filtering: The agent can be configured to ignore emails from personal contacts, non-business domains, or threads that match exclusion patterns (e.g., HR communications, legal correspondence). This prevents personal or sensitive emails from being logged to HubSpot.

Audit trail: Every email read, every HubSpot record update, every sequence enrollment or pause is logged with the user identity, timestamp, and action. Sales leadership can audit the agent’s activity without accessing individual email content. The audit log records what actions were taken, not the content of private communications.

Consent and opt-out: The agent respects HubSpot’s email subscription preferences. If a contact has opted out of marketing emails, the agent will not enroll them in sequences regardless of Gmail engagement signals.

Example use cases

• Real-time engagement alerts: When a high-value prospect opens a proposal email or clicks a pricing link, the agent immediately notifies the rep via Slack or a HubSpot task, enabling timely follow-up while interest is high.

• Automatic email logging: Every email sent from Gmail to a known HubSpot contact is automatically logged to the contact’s CRM timeline, eliminating the need for BCC tracking addresses or browser extensions.

• Intelligent sequence pacing: The agent adjusts HubSpot nurture sequence timing based on prospect engagement patterns. Highly engaged prospects receive accelerated outreach; disengaged prospects are paused before they unsubscribe.

• Sales-marketing coordination: When a rep sends a personal Gmail to a prospect, the agent automatically pauses HubSpot marketing sequences to that contact, preventing conflicting or redundant communication.

• Re-engagement triggers: When a dormant HubSpot contact suddenly opens an old email or visits the website (detected via HubSpot tracking), the agent notifies the rep and suggests a re-engagement approach based on what the contact viewed.

Getting started

Start turning email engagement into pipeline intelligence:

1. Sign up at cloud.agenticcontrolplane.com and create a workspace for your revenue team.
2. Connect your tools by authenticating Gmail and HubSpot through the Data Sources page. Each rep connects their own Gmail account to ensure private inbox access remains per-user.
3. Describe your agent in plain English: “Log my Gmail emails to HubSpot contacts, alert me when prospects show high engagement, and pause nurture sequences when I send personal outreach.” The agent will confirm its scope and begin syncing.