While browsing through the features of Dynamics CRM 2013 one thing that we couldn't find was the Mail Merge functionality.

If you read Scott Durow's blog here you will see how to retrieve the button.
http://www.develop1.net/public/post/How-to-restore-a-hidden-button-on-the-CRM-2013-Command-Bar.aspx

However I found it strange that this functionality would just disappear when it seems to be such a key component of a CRM system.

A colleague then showed me the button is still within CRM its just not on the account and contact entities like it used to be.

To create a mail merge you now need to make sure you have a marketing list. You then have the option of "Mail Merge on Marketing List". I would think that this is a good idea as it restricts the creation of Mail Merges however as we've just discovered this I haven't had a chance to think of the negatives that might exist.