How to change encoding

How to change encoding

Im using the SMTP server to send mail from our website but have ran into some format issues. When using the built in mail my links in emails are fine but when going thru the zoho STMP server the links are disabled. The only thing i can see that's different is the Content-Transfer-Encoding.

My built in email uses Content-Transfer-Encoding: 8bit and zoho uses Content-Transfer-Encoding: quoted-printable. 
Is there a way to change this?