SSRS Dynamic Filenames for Email Subscriptions

There is no feature in SSRS as such but there is a work around for this. You have two options
Option 1:
Instead of emailing it directly first dump the file in fileshare location which can be something like \machine-name\ExportReports\ReportName\ then create a windows job which renames the file to the format you want and emails it in the next step.

Option 2:
Refer to this blog what you want starts from section "Generate a PDF output file programmatically" now you can use this in an assembly then have some scheduling mechanism which picks up the schedule. This then calls the DLL which generates the report and emails it.

Use @timestamp in the name of the file and it will translate at run time.

You cannot specify the report filename in a standard subscription in Reporting Services.

If you have Enterprise edition (or SQL 2012 Business Intelligence edition) you can use the Data-Driven Subscriptions features that allows you to specify the report filename (and other properties) based on data retrieved from a table.

If you have Standard edition, then your options are either of the ones suggested by Bhupendra, or you could look at scripting the report generation using the "rs.exe" utility supplied with Reporting Services and use Database Mail and SQL Server Agent to handle the emailing and scheduling.