The API Key and Secret Key are the values entered into the SMTP parameters when you want to send email directly from your email client or program. Your API Key Information can be found in your SMTP Settings page.
Also, with API Keys, you are able to create sub-accounts on your Mailjet account. This allows to separate your mailings across different API Keys for easier management, account sharing, and reporting.
1. Log in to your Mailjet account.
2. At the upper right corner your screen, click the Mailjet name and choose Account Settings.
3. Under Rest API, Click Master API Key & Sub API Key management.
4. Here are you API Keys.
How to get you Mailjet List ID?
1. In you mailjet dashboard, Click Contacts > Contact Lists.
2. Here is your List ID.