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https://help.tallysolutions.com/docs/te9rel61/Licensing/Error_Code_6436.htm

Error Code 6436: Invalid or incorrect e-mail ID. Enter valid e-mail ID to proceed.

Cause

This error occurs when you enter an invalid e-mail ID (not a valid domain name, or e-mail ID format) or an incorrect e-mail ID.

Solution

You must enter a valid e-mail ID to proceed.