You receive an email with the updated Client Master Report (CMR) for the following reasons:
- You opened a new demat account with Zerodha.
- You recently modified your account details, such as a name change, address change, mobile number change, email change, updating income details or any other change in your demat account.
- Your demat account was converted to a BSDA or a NON-BSDA.
- As per the SEBI circular (PDF), you receive the updated CMR whenever your demat account is mapped or unmapped from a trading account.
- You closed your Zerodha account.
The validity of the updated CMR link is mentioned in the email you received.