Resend integration

Pathbound connects to Resend with an API key and does two things:

1. Reads your Resend contacts, segments, and domains into your Pathbound workspace, where they’re unified with data from your CRM, website analytics, and support tools into a single profile per contact and company.
2. Acts on Resend on your behalf — a set of focused tools that let an AI agent (or a human) manage segments, send a transactional email, or run a broadcast, all with the unified customer context Pathbound already holds.

Unlike Pathbound’s read-only sources, Resend is a two-way integration. The write tools are off by default and enabled per group in your integration settings, so you decide exactly how much Pathbound can do in your Resend account.

Pathbound polls the Resend API on a schedule and reads:

Contacts are matched to your unified profiles by email, so a contact’s Resend segment membership and subscription status show up inline with everything else you know about them.

Pathbound never deletes or edits your Resend data during a sync — the read sync is strictly one-way. The only changes Pathbound makes to Resend come from the write tools below, and only when you’ve enabled them and an agent or user invokes one.

These are the “key tools” Pathbound exposes to AI agents through its MCP server and REST API. Each group is gated on its own toggle in Integrations → Resend, so you can enable reads only, or add exactly the write capabilities you want.

A few things worth knowing:

• Contacts are referenced by Pathbound contact ID, not email. When an agent adds a contact to a segment, Pathbound reads that contact’s email and name from the unified profile, creates the contact in Resend if it isn’t there yet, then adds it to the segment.
• Sends require a verified sending domain. The from address must be on a domain Resend has verified for your account; Pathbound rejects an unverified address and returns the list of usable domains so the agent can correct it.
• Transactional emails can use a Resend template. Pass a body (HTML or text) or a Resend template ID. Broadcasts take a subject and an HTML/text body and support Resend’s personalization placeholders — {{{FIRST_NAME|fallback}}}, {{{LAST_NAME|fallback}}}, {{{EMAIL}}}, {{{RESEND_UNSUBSCRIBE_URL}}}.
• High-impact actions ask first. Deleting a segment, removing a contact from a segment, and sending a broadcast are irreversible or high-blast-radius, so the agent is required to confirm with you — by name — before it proceeds.
• Sends are idempotent. Transactional sends and broadcast creation are deduplicated within a 24-hour window, so an accidental double-call won’t send twice.

1. In the Resend dashboard, create an API key. Give it Full access if you want Pathbound to sync contacts/segments/domains and manage them; a sending-only key can send email but can’t read or manage the rest. Resend keys start with re_.
2. In the Pathbound app, open Integrations and select Resend (under Email).
3. Paste the API key and click Connect. Pathbound validates the key against Resend, then stores it encrypted.
4. Choose which write tools to enable under the integration’s settings. Everything except the read sync is off until you turn it on.

Pathbound begins syncing on the next scheduled run.

• Poll-based. Pathbound calls the Resend API on a schedule (every two hours by default); there are no webhooks to configure on your side.
• Full re-walk each run. Resend doesn’t expose an “updated since” cursor for contacts, so each sync re-reads the full contact list and reconciles changes. Steady-state runs that find no changes do no extra work.
• Rate-limit aware. Requests are paced adaptively under Resend’s per-team rate limit and back off automatically on a 429, so the sync never trips your account’s limits.
• Segment membership is folded onto contacts. Pathbound resolves which segments each contact belongs to and stamps it on the unified profile, so agents can filter and target without extra lookups.
• Stale detection. Contacts removed in Resend are marked deleted in Pathbound on the next sync (never before a successful, non-empty walk, so a transient blip can’t wipe your data).

Once synced, open any contact in Pathbound:

• The contact’s Resend segment membership and subscription status enrich the unified profile alongside your other sources.
• Emails an agent sends through Resend are logged to the contact’s timeline with attribution.

The same data and tools are available to AI agents through Pathbound’s MCP server and REST API — including the query_resend_data read tool (contacts, domains, segments, and a summary) and the segment, send, and broadcast write tools listed above.

• Your Resend API key is encrypted at rest and scoped to your tenant, isolated from other Pathbound customers.
• If Resend ever rejects the key (401/403), Pathbound marks it invalid and stops advertising the write tools until you reconnect — so a rotated or revoked key fails safe.
• Write tools are opt-in per group, and transactional/broadcast sends can only originate from a domain you’ve verified in Resend.
• See our Privacy Policy and Terms of Service.

To stop the sync and revoke access:

1. In the Pathbound app, open Integrations → Resend.
2. Click Disconnect.

Disconnecting deletes the stored Resend API key from Pathbound. For a full revoke, also delete the key in your Resend dashboard.

• “Invalid Resend API key” on connect. The key must start with re_ and be active in Resend. Create a fresh key and try again.
• Contacts or segments aren’t syncing. A sending-only key can’t read them — reconnect with a Full access key.
• A send is rejected with “no verified domain.” Verify a sending domain in Resend first, then use a from address on that domain. Pathbound returns the list of usable domains when it rejects one.
• “Your plan includes N segments.” Resend caps segments by plan. Delete an unused segment or upgrade your Resend plan to add more; Pathbound surfaces Resend’s message verbatim.
• The write tools don’t appear to an agent. They’re enabled per group in Integrations → Resend — confirm the relevant toggle (resend_manage_segments, resend_send_email, resend_manage_broadcasts, resend_send_broadcasts) is on and the key is valid.

Need help? Email [email protected].