Cannot send emails to Gmail addresses

Cannot send emails to Gmail addresses

I have a zoho hosted account that cannot send any emails to a Gmail address.  I receive the following bounce back that says it's an invalid address, but I know that the address is typed correctly.   Everything is spelled correctly and there are no additional spaces or punctuation.  This error just started today and I was able to send emails to Gmail just fine before this.

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This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.

 INVALID_ADDRESS


Reporting-MTA: dns; mx.zohomail.com
Arrival-Date: Tue, 15 Dec 2020 13:47:18 -0800


Status: 550
Action: failed
Last-Attempt-Date: 15 Dec 2020 21:47:20 GMT
Diagnostic-Code: 5.1.1 The email account that you tried to reach does not exist. Please try
            5.1.1 double-checking the recipient's email address for typos or
            5.1.1 unnecessary spaces. Learn more at
            5.1.1 https://support.google.com/mail/?p=NoSuchUser g192si36636pgc.567 - gsmtp