When to use Migrating Email Router Data

Hi all,

Our current organization is CRM2011 we are upgrading it to 365( Our servers are totally changed)

In our upgrade process we restore back up of our organization from 2011 and upgrade it till 365.

Currently in 2011 we have email router. In new 365 we also need to set up Server Side Email. (CRM on premise with our own Exchange server).

I know that I have to below steps based on the below link (Connect Dynamics 365 (on-premises) to Exchange Server (on-premises))
https://technet.microsoft.com/en-us/library/mt622062.aspx

1-Create an email server profile

2-Configure default email processing and synchronization

3-Configure mailboxes

4-Approve email

5-Test configuration of mailboxes

6-Test email configuration for all mailboxes associated with an email server profile

The question that I have is do I have to use Migrate Email Router Dataor not and if the answer YES when and why?

What happens if I Don't.

I appreciate your help!

Maryam