To my surprise it is not possible to send email to company-based lists.
We have an integration between CRM system Koho and HubSpot, and store a lot of business critical information about contracts and customers in Koho. The integration pushes data to HubSpot (custom fields) which has been selected as the agile tool for communication and marketing to our customers. Due to the company dependent information, I found out the hard way we are not able to use company-based lists to reach out to our customers.
I hope you would develop this feature very soon. Usability of HubSpot would be much better without exporting data to excel and then importing the same data back. It just doesn't make any sense.
The experience was totally unexpected not being able to send to a company-based list and it caused a lot of unnecessary trouble in a tight time schedule. I hope you would at least give information about the absence of the feature in the list and email tools.