An article has been posted at Ars Technica that Paypal have blocked some of the old versions of web browsers.

The company states: “In our view, letting users view the PayPal site on one of these [older] browsers is equal to a car manufacturer allowing drivers to buy one of their vehicles without seatbelts.”

First-tier browsers including Firefox 2 and IE 7 users will be able to do their business normally while warning messages will be posted on users who logs on to Paypal while using old versions of web browsers.

This decision was made to reduce phishing attacks.

Source: Ars Technica