You can synchronize your contact list made with one of the following plugins:
- Ninja Forms
- Contact Form 7
- Formidable Forms
- Gravity Forms
Jackmail also allows you to make request to an existing html database using POST request
When installing Jackmail, a step is asking you if you want to synchronize existing active forms plugins with Jackmail.
If the plugin is installed after Jackmail, a message will say that it is now synchronizable.