Blacklists are a feature where you can add companies which you do not want to contact.
In order to reach the blacklist option, you need to go to profile settings from the dashboard.
In the profile settings, in the upper right corner, you can see a button called Blacklist. Click on it.
It will open a pop-up page with some explanations about the blacklist and fields where you can fill in the companies. You can choose between three types of fields - Exact match (there you right the specific and complete company names which you want to avoid), Contains (here you ca write only a specific word which will lead to Expandi avoiding companies whose name contains this word), Starts with and Ends with.
Once you've filled in the company names which you don't want to connect to or message, click on Apply in the bottom part of the page.