This article explains how to transfer folders and emails from your Mozilla Thunderbird account to Mail Business:

Transfer folders

  • Select the folder in your Thunderbird account that you wish to transfer to Mail Business.
  • Using the left mouse button, drag the folder to the desired location in your Mail Business inbox.

Transferring emails

  • Select the emails in your Thunderbird account that you want to transfer to Mail Business.
  • Go to Message > Copy To. Select the Mail Business account and the folder where you want the emails to be stored.