Unable to Send Email/SMTP connect() failed

Unable to Send Email/SMTP connect() failed

I have tried to send emails using the information provided here https://mail.zoho.com/zm/#settings/all/mailaccounts and here https://www.zoho.com/mail/help/zoho-smtp.html.
 
However, I keep getting the same error: SMTP connect() failed.

Any help would be greatly appreciated.