Exchanges send you weekly SMS and email updates about your funds and securities balances to prevent misappropriation of funds, as required by SEBI regulations (PDF).
The fund balance shown in your SMS and email reflects the balance as per the date mentioned in the message, not the date you received the SMS or email.
The format of the email regarding funds and securities balances from the exchanges is as follows:
BSE
NSE
MCX
The total number of ISINs may appear as zero in these notifications. This represents the number of ISINs in the broker's pool account, not your individual demat account holdings.