You can use specific markup in the emails you send from within BestInvoicing. You may use different email templates, each with their own colors and logo, in case you are carrying out different activities with different style schemes under the same company/VAT number.
Editing Email Templates
Navigate to your email address in the top right corner of BestInvoicing and click the menu
Select 'Company Settings'
Select the tab 'Email Settings' and scroll to the bottom of the page
In this section, you'll be able to modify the look of your email message. By default BestInvoicing proposes a template 'With Layout', which you can further modify using the visual editor.
In order to add your own company elements to the template, click the yellow button 'Personalize Template'.