we are a small firm considering using Zoho Invoice. We are user of Gmail Enterprise. 

We are currently testing Zoho invoicing and found that EVERY email we receive OR send to OR from anyone has a Zoho Invoice at the bottom of each email. It is really annoying, does not give a professional aspect and worse does not look like something secured (in particular for an invoicing system

Is there any explanation and above all how to get rid of it (or get rid of Zoho if there is no other solution)

please find attached a screen capture as an example

Thanks in advance

Jerome