The Campaign Monitor integration with OptiMonk allows you to have subscribers added to your Campaign Monitor mailing list when they fill out an OptiMonk popup form. It may come in handy if you run marketing campaigns on a regular basis, so that the subscribers who signed up via OptiMonk will also get news about your upcoming promotions and news.
Step 1: Find Your Campaign Monitor API Key
Click on Account Settings in the top menu bar, then click on the API keys button in the right column menu.
Step 2: Connect Campaign Monitor to OptiMonk
Click on the Show API key, right-click and copy the value.
Then, paste the API key in the API key field in your campaign settings on OptiMonk. After you paste the API key in the field on OptiMonk, click on the Test Connection button next to the field.
Step 3: Select Your Client in OptiMonk
After a successful test, find the appropriate client in the Client's name drop-down menu.
Step 4: Choose Your Subscriber List
Choose the appropriate list you would like to add the subscribers to from the List name drop-down menu.
Step 5: Navigate to Your List in Campaign Monitor
On the Campaign Monitor site, choose the Lists & Subscribers tab, then select the list you are adding the OptiMonk subscribers to.
Step 6: Access Custom Fields
Click on Custom fields in the right column menu.
Step 7: Add the OptiMonk Custom Field and Finalize
Click on Add custom field and add a new custom field with the value: OptiMonk.
Check that the Data Type is Text.
Then, in your campaign settings on OptiMonk, click on Refresh next to the Source Field name drop-down menu. After you click Refresh, choose the appropriate name from the drop-down menu.

