Generally, the company email address is used for sending invoices. You can however also set a specific email address only for sending invoices.

Here is how to set or change it:

1. Navigate to Settings and click on Company information
2. Click on the pencil next to your company entity
3. In 'Company details', fill out the field 'Invoicing email'
   
4. Click on Save and close
5. All invoices sent from your company will be sent from this email address.