What steps should administrators take to configure SharePoint 2013 for e-discovery across Exchange?
Brien Posey, Microsoft MVP: SharePoint 2013 has a module called the eDiscovery Center, which is a special type of site collection. Microsoft designed it so you can perform e-discovery not just within SharePoint, but also in Exchange Server and Microsoft Lync.
The first requirement, if you're going to do e-discovery across Exchange and SharePoint, is that both Exchange and SharePoint have to exist within a common domain, inside a common forest. Also, SharePoint has to be configured to support SSL encryption. You have to have a certificate that's both valid and trusted by the other servers in your organization.
There's also a component called the Microsoft Exchange Web Services Managed API. You have to install version 2.0 of that API on every SharePoint server in your organization. This is something you can get for free from the Microsoft Download Center. Once you install that component on each SharePoint server, you must reboot the server or perform an IIS [Internet Information Services] reset on the server.
Those are just the prerequisites to make e-discovery across Exchange possible. There's also a trust relationship you're going to have to put into place before you can actually do e-discovery. Specifically, you have to configure server-to-server authentication for Exchange to SharePoint, and then you have to configure server-to-server authentication from SharePoint to Exchange -- so you have to do it on both sides. This is done by running PowerShell commands, which is something you can find on the Microsoft TechNet site.
Once you get the trust relationships in place, there's still a permissions issue. You have to grant permissions to perform e-discovery. Exchange Server 2013 has its own e-discovery portal that gets exposed through the Exchange Administrative Center. Microsoft wants Exchange administrators to be able to perform e-discovery even if they don't have SharePoint. SharePoint is designed to take advantage of the same permissions that are used within Exchange to perform e-discovery. If you want to allow your legal team to do e-discovery across Exchange, then go into Exchange Server and assign your legal team the Discovery Management role, and only then will they have the permissions they need on the Exchange side.