# How to Sync GrowSurf Participants to a Resend Segment

> Connect Resend to GrowSurf with a Full access key, choose a Segment, and let referral Contact Properties stay current on every Contact.

- URL: https://growsurf.com/integration-guides/resend-referral-contact-sync/

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[← View All Guides](/integration-guides/)

Point GrowSurf at a Resend Segment and it keeps Contacts and their referral Contact Properties current on its own.

Want the full setup walkthrough?

Use these docs for exact setup steps, supported fields, and troubleshooting.

[GrowSurf Resend setup guide](https://docs.growsurf.com/integrations/resend) [Resend Contact Properties docs](https://resend.com/docs/dashboard/audiences/properties)

GrowSurf adds and updates Contacts in the Resend Segment you choose, and creates the Contact Properties that hold each participant’s referral link, referral counts, referrer details, and milestone progress.

Use this guide to get the sync running. Once it is, those properties are available to any Broadcast you send to that Segment.

## Integration Steps

### Create a Resend API key with Full access

In [Resend > API Keys](https://resend.com/api-keys), select **+ Create API key**, name it, and choose **Full access** under Permission. A sending-only key cannot read Segments or manage Contacts, so it will not work here. Copy the key from the confirmation screen — Resend does not show it again.

### Find Resend in your GrowSurf program

Searching for Resend in the GrowSurf Program Editor integrations listSearch the integrations list in Program Editor > 4. Options > Integrations.

Connect Resend before you import participants so the sync covers everyone from the start.

### Paste the key

The Resend API key field in the GrowSurf Program EditorPaste the Full access key and select Submit.

GrowSurf stores the key securely and does not return it to the dashboard.

### Choose the Segment that receives participants

The connected Resend integration in GrowSurf with a Segment selectedPick the Segment GrowSurf should keep current. Use the refresh icon if a new Segment is missing.

Pick your Segment from the dropdown. If one you just made in Resend is not listed, select the refresh icon beside the dropdown to reload it. Saving the Segment is what starts the sync and creates the Contact Properties.

### Know which properties you get

GrowSurf creates these account-level Contact Properties in Resend:

| Contact Property | Property key | Type | What it holds |
| --- | --- | --- | --- |
| GrowSurf Share URL | grsf_share_url | String | The participant’s unique referral link |
| GrowSurf Participant ID | grsf_participant_id | String | The participant’s GrowSurf ID |
| GrowSurf Referral Status | grsf_referral_status | String | CREDIT_PENDING, CREDIT_AWARDED, or CREDIT_EXPIRED |
| GrowSurf Participant First Name | grsf_participant_first_name | String | The participant’s first name |
| GrowSurf Participant Last Name | grsf_participant_last_name | String | The participant’s last name |
| GrowSurf Referrer First Name | grsf_referrer_first_name | String | The referrer’s first name, when there is one |
| GrowSurf Referrer Last Name | grsf_referrer_last_name | String | The referrer’s last name, when there is one |
| GrowSurf Referrer Email | grsf_referrer_email | String | The referrer’s email, when there is one |
| GrowSurf Total Referral Count | grsf_total_referral_count | Number | All-time referral count |
| GrowSurf Monthly Referral Count | grsf_monthly_referral_count | Number | Referral count for the current month |
| GrowSurf Previous Monthly Referral Count | grsf_prev_monthly_referral_count | Number | Referral count for the previous month |
| GrowSurf Next Milestone | grsf_next_milestone | String | The next milestone message, on programs with milestone rewards |
| GrowSurf Next Monthly Milestone | grsf_next_monthly_milestone | String | The next monthly milestone message, when there is one |
| GrowSurf Total Invite Count | grsf_total_invite_count | Number | All-time invite count |
| GrowSurf Total Impression Count | grsf_total_impression_count | Number | All-time referral-link view count |

If the program already has participants, use the [existing-participant sync options](https://support.growsurf.com/article/385-how-can-i-sync-my-growsurf-participants-to-my-esp) to send their current referral data across.

## Tips

#### Full access, not a sending key

This is the single most common setup failure. The key needs to read Segments and manage Contacts and Contact Properties, which only Full access grants.

#### Do not delete the Segment you selected

If the Segment is removed in Resend, pick an existing one in GrowSurf and save again. The sync has nowhere to write until you do.

#### Property keys are case sensitive

Resend treats `grsf_share_url` and `GRSF_Share_URL` as different keys. Use the names exactly as GrowSurf creates them when you reference them in a Broadcast.

Recommended Guides

[Resend logo How to Add Referral Links to Resend Broadcasts Drop each participant’s own referral link and progress into a Broadcast with Resend’s Contact Property syntax. View Guide →](/integration-guides/resend-referral-broadcast-personalization/) [SendGrid logo How to Build SendGrid Referral Email Templates with GrowSurf Sync participants into a SendGrid marketing list, then use GrowSurf referral fields inside reusable email templates. View Guide →](/integration-guides/sendgrid-referral-email-templates/) [Mailchimp logo How to Build Mailchimp Referral Email Campaigns with GrowSurf Sync GrowSurf merge tags into your Mailchimp Audience so every referral email can show the right share link, progress update, and reward message. View Guide →](/integration-guides/mailchimp-referral-email-campaigns/)

## FAQ

#### Do I have to create the Contact Properties myself?

No. Selecting a Segment in GrowSurf creates them for you and keeps their values current.

#### What happens if Resend is briefly unavailable?

GrowSurf retries temporary provider errors for up to seven days. A participant’s activity log shows the result of each attempt.

#### Where do I use these properties?

In Broadcasts sent to that Segment. See [adding referral links to Resend Broadcasts](/integration-guides/resend-referral-broadcast-personalization/) for the syntax.

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