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The Campaign Monitor integration allows you to instantly route form respondents directly into your Campaign Monitor subscriber lists. It features deep custom field mapping, robust consent tracking options, and granular control over autoresponder re-triggers.

Business Use Cases

Marketing Automation

Inject leads into an automated drip campaign the moment they submit a form.

GDPR Compliance

Ensure strict data privacy by explicitly declaring the respondent’s consent_to_track status upon insertion.

Win-back Campaigns

Use the resubscribe feature to automatically revive dead leads who fill out a new form after previously unsubscribing.

Step 1: Global Connection

Before you can push data to Campaign Monitor, you must authorize Flex Forms to communicate with your account.
1

Locate your API Key

Log into your Campaign Monitor dashboard. Navigate to Account Settings → API keys. Generate and copy your API Key.
2

Establish the Connection

In your Flex Forms dashboard, open Integrations in the left rail (next to Global Settings). Locate the Campaign Monitor card and enter your API Key.
3

Test and Verify

Click Save & Verify. Flex Forms will ping the https://api.createsend.com/api/v3.3 endpoint to ensure the credentials are valid and that your client lists can be fetched.

Step 2: Form-Level Configuration

Once the global connection is established, you must activate the integration on a per-form basis. Open your specific form in the Studio and navigate to the Integrations tab.

The Masterclass: Data Mapping & Subscriber Controls

When mapping data from Flex Forms to Campaign Monitor, the system fetches all of your lists across all of your clients via live remote_select.
remote_select
required
Target Contact List Loaded live from your Campaign Monitor account. All new submissions will be added to this specific list.
select
required
Email Field Select the block on your form that collects the respondent’s primary email.
select
Name Field Optional. Lists only Name blocks on this form. Leave empty to use the form’s Name field automatically.
textarea
Custom Field Mapping Map your form block answers to Campaign Monitor Custom Fields.Syntax: CampaignMonitorFieldKey=flex_forms_block_name (One per line).Example Mapping:

Advanced Subscriber States

Campaign Monitor allows for very strict control over how a subscriber enters (or re-enters) a list.
toggle
default:"false"
Resubscribe previously unsubscribed contacts When enabled, if a respondent previously clicked “Unsubscribe” on one of your emails, but then voluntarily fills out this Flex Form, they will be forcibly moved from the ‘Unsubscribed’ state back to the ‘Active’ state on the list.
toggle
default:"false"
Restart subscription-based autoresponders If this contact already existed on the list, enabling this toggle will force Campaign Monitor to restart any welcome sequences or autoresponders attached to the list for this specific user.
Consent to Track (GDPR) Controls email tracking behavior for this specific respondent.
  • Yes: Consent is granted. Campaign Monitor tracks opens and clicks.
  • No: Consent is denied. Campaign Monitor will not track engagement.
  • Unchanged: Only use this if updating an existing subscriber whose consent status shouldn’t be overridden.

Configuration Reference

The following advanced settings are available in the Flex Forms UI for this integration. Use this reference to understand exactly how each field impacts the API payload.

Global Settings

Located in Integrations in the Flex Forms left rail.
password
required
Campaign Monitor API Key Your master API key. Generate this in your Campaign Monitor account under Account Settings → API keys.

Form-Level Settings

Located on the form hub Integrations tab for a specific form.

Subscriber Placement

remote_select
required
Target Contact List Loaded live from your Campaign Monitor account. All new submissions will be added to this specific list.
select
required
Email Field Select the block on your form that collects the respondent’s primary email.
select
Name Field Optional. Lists only Name blocks on this form. Leave empty to use the form’s Name field automatically.

Field Mapping

textarea
Custom Field Mapping Map your form block answers to Campaign Monitor Custom Fields.Syntax: CampaignMonitorFieldKey=flex_forms_block_name (One per line).
remote_select
Available custom fields (reference) A read-only helper. Select a list to view its custom fields and their exact keys, so you can easily copy/paste them into the custom_field_map above.

Advanced Options

toggle
default:"false"
Resubscribe previously unsubscribed contacts When enabled, if a respondent previously clicked “Unsubscribe” on one of your emails, but then voluntarily fills out this Flex Form, they will be forcefully moved back to the ‘Active’ state.
toggle
default:"false"
Restart subscription-based autoresponders If this contact already existed on the list, enabling this toggle will force Campaign Monitor to restart any welcome sequences.
Consent to Track (GDPR) Controls email tracking behavior for this specific respondent (Yes, No, or Unchanged).
Last modified on September 7, 2026