This article walks you through connecting MailerLite to an OptiMonk campaign. Once you are done, everyone who fills out your popup form is added to the MailerLite subscriber group you picked — no exports, no copy-paste.
Before you start: you need a campaign whose popup is already built (the field mapping is read from the input fields of your popup) and a MailerLite account.
Good to know: MailerLite is a legacy integration. You cannot start a new MailerLite connection from the campaign's Integrations tab — the provider list does not offer it. You connect the account once in the classic OptiMonk admin, and from then on it behaves like every other integration here: you attach it to a campaign, pick a list and map the fields in the Integrations tab.
1. Get your MailerLite API key
Open your MailerLite dashboard and click your profile icon at the top right of the screen, then click Integrations.
On the following screen, select Developer API.
Click Copy to copy the API key.
OptiMonk's own hint for this field says it in one line: To locate your API key: Log in to your MailerLite dashboard. Click on your account name in the top right corner of the site and select the "Integrations" option. Then select "Developer API". Your API key will be listed under the "API Key" label.
2. Connect MailerLite in the classic OptiMonk admin
In OptiMonk, open the account menu and choose Go to classic admin. You are signed in there with the same account; no second login.
In the classic admin, open the campaign you want to connect and go to its integration settings, then add a new MailerLite integration.
Paste the key into the API key field, give the connection a name you will recognise later, and save it.
Once the connection exists on your account, you can use it in the new OptiMonk app on any campaign — you only have to do this step once per MailerLite account.
3. Attach it to your campaign in OptiMonk
Open Campaigns in the left menu and click the campaign you want to connect with MailerLite.
Open the Integrations tab of the campaign.
Click Add integration. If this is the campaign's first one, the same step is offered as Connect your email or SMS tool.
Provider step: your MailerLite connection is listed at the top under Your connected accounts, with the name you gave it in the classic admin. If you did not name it, it appears as MailerLite. Click it. If the list is long, type into the Search providers… box.
List step: pick the subscriber group new signups should join, then click Continue. Use Search lists… if you have many.
Field mapping step: decide where each popup field goes in MailerLite (see below), then click Save integration.
That's it. Whenever a visitor signs up through your popup, they are added to the MailerLite group you picked. Their data also stays in OptiMonk — you find it under Leads in the left menu.
Draft vs. live: if the campaign has not been published yet, the integration is shown with a Draft pill and the note Saved as draft — it goes live when you publish the campaign. On a published campaign it shows as Active and is applied right away.
Field mapping
The mapping table has two columns: Popup field on the left (every input your popup collects) and Mailer Lite field on the right. OptiMonk pre-fills the mapping with its own suggestions, so in most cases you only need to check it — MailerLite's standard name and email fields are matched for you.
The email row is fixed — it always maps to MailerLite's email field.
Pick Don't sync for any popup field you don't want to send.
Under Static fields, you can send a fixed value with every submission, for example, the source of the subscriber. Click Add static field, type the value on the left, and choose the MailerLite field on the right.
Change or remove the integration
The Integrations tab lists every integration on the campaign with its list name.
Change list reopens the wizard at the list step, and from there you can walk on to the mapping.
Remove takes the integration off this campaign: Remove from this campaign? The account connection stays and can be added again. Your MailerLite credentials are not deleted, so you can reuse them on another campaign.
Check that it works
Fill out your own popup once on the live site, then look for the subscriber in MailerLite — and in OptiMonk under Leads. You can also just ask the assistant on the campaign page ("where do the subscribers go?"): it answers from the campaign's real configuration.