Targeted legal holds in Google Vault

Vault admins have had the ability to put an entire user account on hold to preserve messages in that account. Next week we will roll out a new feature that will allow admins to also have the option to target specific messages—for example, by date or with certain terms—for indefinite preservation in Vault.

Editions included: 
Google Apps for Business, Education, and Government

For more information:
https://support.google.com/vault/answer/4409174

Reference by : http://www.google.com/