A Retention policy is a group of retention tags that can be applied globally to all the users . This helps us in maintaining the email lifecycle globally from the server end.

This will help users and the organization in terms of not loading up the server with unwanted old emails and end users maintaining their mailbox not as a part of their daily task. Messages are expired based on settings defined in the retention tags linked to the policy. There is no difference in retention policies from exchange 2010 to 2013 apart from the configuration part.

Below are the steps to set up retention policy in Exchange 2013.

1)      Open EAC –> Select Compliance Management -> and click on retention policies

2) We have 3 options as shown above and we can choose as per the option and click on the + sign

3) In the next window you get the space where you can type the retention policy name. You can type any desired name since this name will not be displayed to the end users.

4) Then we need to choose the required retention tags and add them as shown in the below screenshot.

Then we have options to edit the created retention policy and we can add, edit and remove the retention tags any time.

Then use EMS to apply retention policy to single user with the below command

Set-Mailbox “Exchangequeryadmin” -RetentionPolicy “Exchangequerytest”

We can refer the below article to apply retention policy to bulk/group users

http://technet.microsoft.com/en-us/library/dd298052(v=exchg.150).aspx

Thanks 

Sathish Veerapandian

MVP – Exchange Server