avast adds advertisments to my emails

[REDACTED]

I use gmail and Avast Free Antivirus and Firefox w/ Avast Internet Security. It happens when I respond and quote - not when I send first  email. I want to know how to turn this off and keep my software.

It doesn't render. This is how ad looks like:
<div id="DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br />
<table style="border-top: 1px solid #D3D4DE;">
        <tr>
      <td style="width: 55px; padding-top: 18px;"><a
href="https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail"
target="_blank"><img
src="https://ipmcdn.avast.com/images/icons/icon-envelope-tick-round-orange-animated-no-repeat-v1.gif"
alt="" width="46" height="29" style="width: 46px; height: 29px;"
/></a></td>
                <td style="width: 470px; padding-top: 17px; color: #41424e;
font-size: 13px; font-family: Arial, Helvetica, sans-serif;
line-height: 18px;">Wolny od wirusów. <a
href="https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail"
target="_blank" style="color: #4453ea;">www.avast.com</a>               </td>
        </tr>
</table>
<a href="#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2" width="1" height="1"></a></div>

[Pondus]

Try this   https://www.avast.com/faq.php?article=AVKB97#artTitle