i need to append timestamp in the filename which i am attaching to send report in email

suggest solution other than fileshare

Hi,

As you can see, we can use a variable to get dynamic FileName for the report or attachment only when the subscription is using Windows File Share delivery extension. However, you can implement a custom delivery extension to achieve your goal, please see:
http://msdn.microsoft.com/en-us/library/ms154050.aspx

Besides, you can refer to the Printer Delivery Extension Sample provided by SQL Server Reporting Services Samples:
http://msftrsprodsamples.codeplex.com/

Similar thread for your reference:
FileName for datadriven subscription delivered by email

Regards,
Vic