Getting 'Unknown user" status when my spam filter service connects to port 25 of mx.zohomail.com ... (Can we fix this)?

Getting 'Unknown user" status when my spam filter service connects to port 25 of mx.zohomail.com ... (Can we fix this)?

Hello:

Earlier today I signed up for a business/organization account with Zoho, and registered my domain in it,
example.com (let's pretend it's that one for security sake).

The email address I used to sign up with, and which is used for Admin purposes is: john.doe@example.com
The second email address I created, which is meant to actually send/receive emails, is : jdoe@example.com

The issue :: Tenlets to test STMP port 25 show this
:
- Using telnet to send test emails over mx.zohomail.com:25 works for john.doe@example.com
- However doing the same for jdoe@example.com does not work. It returns a "Unknown user..." when
  I specify that "RCPT TO" address. But this email address, as stated, is configured in Zoho. 

So how do I enable jdoe@example.com to successfully authenticate on mx.zohomail.com:25 , just like
john.doe@examle.com

Thank you.