Using Gmail-Apps account with Zoho Mail

Using Gmail-Apps account with Zoho Mail

Hi can you please help me with this error when trying to send a message using my email address and not Zoho,
Change required from Gmail side or Zoho Mail side? Thanks for support.
Unable to connect SMTP server:smtp.gmail.com Reason:Authentication failed:535-5.7.8 Username and Password not accepted. Learn more at535 5.7.8 http://support.google.com/mail/bin/answer.py?answer=14257 i2sm19096689pdk.70 - gsmtp