The problem is that clients still use these browsers and expect to view your site properly with their legacy browsers. So, when do you stop supporting old browsers?
Option 1 – follow the big companies
Big companies like Google, Yahoo, and Microsoft announce their support for legacy browsers. When they stop supporting an old browser you know you can start doing that too.
- For yahoo check out – http://developer.yahoo.com/yui/articles/gbs/
- For Google check out – http://googledocs.blogspot.com/2010/01/web-browser-support-for-docs-and-sites.html
- For Microsoft check out – http://office.microsoft.com/en-us/help/HP010294751033.aspx
Option 2 – Check out browser statistics
If a browser costs you 10,000$ to support, but has only 0.5% market share, you have a good business case to removed it from your supported list.
Here is an example of where you find browser usage statistics – http://www.w3schools.com/browsers/browsers_stats.asp
Here is another example –
Option 3 – negotiate with your clients
This is a tricky one, business owners have limited budget, you need to agree with your business owner which browsers should be supported. If he/she insists on supporting old browsers they need to know how much they are going to pay for that, and how much are they going to loss in other fields, such as functionality.
Leverage your knowledge
Know your clients, if you are developing an application for Mac users, you should definitely support safari. If you are developing an application for internal use, you can mandate a much smaller set of supported browsers.
Rule of Thumb
As a rule of thumb, I recommend supporting at least two of the latest versions of most popular browsers.