Couldn't able to configure ssmtp on Ubuntu to use zoho mail

Couldn't able to configure ssmtp on Ubuntu to use zoho mail

1) Here is my 
/etc/ssmtp/ssmtp.conf looks like
mailhub=smtp.zoho.com:465
rewriteDomain=zoho.com
AuthUser=info@xxxxxxx.in
AuthPass=*********
UseSTARTTLS=YES
FromLineOverride=yes

2) Here is the content of /etc/ssmtp/revaliases
root:info@xxxxxxx.in:smtp.zoho.com:465

I'm getting the following error
[<-] 220 relay.v.fozzy.com ESMTP Exim 4.91
[->] EHLO test
[<-] 250 HELP
[->] AUTH LOGIN
[<-] 503 AUTH command used when not advertised
sendmail: Server didn't like our AUTH LOGIN (503 AUTH command used when not advertised)

How can I resolve this? Any help would be appreciated!