Update Mailchimp contacts with their unique share link and referrer information.

How to get your Mailchimp API key

Step 1: Log into your Mailchimp account

Step 2: Once logged in, click on the top-right account dropdown, then click on Account

Step 3: On your Account page, click on Extras > API keys

Your Mailchimp Account page

Step 4: Scroll to the API keys section and copy the contents in the API key field (or click the Create A Key button to create a new API key)

Your Mailchimp API keys page

Sync with your Mailchimp Audience

Step 1: In the GrowSurf Campaign Editor - Options step, paste the Mailchimp API key into the Mailchimp API key field, then click Submit

The GrowSurf Campaign Editor - Options page

Security First

API keys are encrypted before they are saved into GrowSurf. If you ever need to reset your Mailchimp integration, you must disconnect Mailchimp and reconnect with your API key again.

Step 2: Once submitted, choose the Mailchimp Audience that you want to automatically sync to. GrowSurf will then add/update your Mailchimp contacts every time a new participant is added or referred in your referral campaign.

NOTE: GrowSurf will automatically create these new *|MERGE|* tags for your Mailchimp Audience.

*|MERGE|* tag





Participant's Share URL



Participant's ID




Referrer's First Name




Referrer's Last Name




Referrer's Email


Step 3: You can now use these *|MERGE|* tags in your Mailchimp email templates. Whether you launch a new marketing campaign or have an automated drip campaign going on, make sure to always include *|SHAREURL|* at the bottom of your emails in order to provoke your contacts to refer their friends!

Learn more about Mailchimp merge tags here.

Troubleshooting Tips

  • If the new participant isn't being added to Mailchimp:

    • Activity logs will denote if a participant was added to Mailchimp or if they were failed to be added. (In the case of failure, GrowSurf will re-attempt to add them for 7 days).

    • Some failures are fatal to Mailchimp and cannot be re-attempted. One example is the 'Forgotten Email Not Subscribed' error, which means that the Mailchimp contact was permanently deleted from the Mailchimp Audience and so you must manually re-add them.

    • Make sure that your campaign Share URL is valid (e.g, the unique referral link that looks like An invalid URL such as https://thiswontwork will result in the new participant not being saved to Mailchimp.

    • If the participant email contains a + symbol within the email, Mailchimp will only allow a certain number of these emails into a list before it errors with a message such as has signed up to a lot of lists very recently; we\'re not allowing more signups for now

    • If you are seeing a "Your merge fields were invalid...Please enter a value" error message (see image), this means that GrowSurf has tried to save a new participant to Mailchimp, but could not due to a missing merge field value. This could happen if you had initially connected GrowSurf to Mailchimp, but you later made one or more Mailchimp merge fields in your Audience required. To fix this, you must uncheck the required field(s).

  • If you have Final Welcome Email enabled in Mailchimp, but you are not seeing the email sent to new Mailchimp contacts:

    • The Final Welcome Email will not be sent out because GrowSurf adds Mailchimp contacts with a status of subscribed. This means that new contacts automatically double opt-in. To send Mailchimp welcome emails, you will need to Create an Automated Welcome Email.

  • Once a participant is added to Mailchimp, that is final. GrowSurf will never update participant information in Mailchimp nor delete them.