Not a RBI authenticated transaction message from HDFC bank

Your trx is debited to HDFC Bank CREDIT Card for Rs. xxxxxxx….. This is not an authenticated trx as per RBI Mandate effective 1 May 12.
You can receive such a message from HDFC bank for your transactions like

• Standing Instructions for bill payments
• Subscription charges to magazines where you had given credit card details in the subscription form.
• Use of your credit card by your travel agents/airline or hotels with whom you have shared your credit card details

No need to worry about as it is only for the information. And bank also mentions here that they are going to do the transaction nevertheless, “We assure you that your transactions will be processed in the same manner as its being done presently”

Normal account and Overdraft account Difference

Overdraft is a type of bank account where an extension of credit from a bank or a lending institution beyond the available balance in the current account can be made. Whereas the normal account cannot avail this feature.
Overdraft account is usually used by companies, business houses where there is a high volume of transactions. These parties can enter into an agreement with the bank on the terms of Overdraft account like maximum credit limit, maximum default time, interest rates etc depending upon their respective business and volumes.

Here is a small illustration on how overdraft works