cannot send email from external application

cannot send email from external application

I'm trying to send emails from my gravity forms contact form in my website using my zoho account smtp. I put the credentials:

username: ventas@amytours.com
password: ******
smtp server: smtp.zoho.com
tls / 587
smtp authentication: yes

but i'm getting this error:

2016-10-14 16:39:50 Connection: opening to smtp.zoho.com:587, timeout=300, options=array ( ) 2016-10-14 16:39:51 SMTP ERROR: Failed to connect to server: Connection refused (111) 2016-10-14 16:39:51 SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting