A proper name for Microsoft software
Solution 1:
Here I would propose enterprise software. As a marketing buzzword (buzzphrase?) it admittedly has become rather inexact. Nevertheless, it encapsulates what the three examples have in common, aside from their manufacturer: they are "heavy-duty" software products that the typical end user does not interact with directly; they are useful (or cost-effective) only at the enterprise level (i.e. for a large or complex organization). An end user would almost never see screens for managing Exchange, for example. He or she would likely interact with Outlook, and Outlook communicates with and through Exchange. He or she would almost never write or extract data directly from SQL Server, but use another application or website to do so.
Business solutions software is somewhat orthogonal to "enterprise software," since business software would include software aimed at businesses which are too small or simple to require products as heavy as SharePoint or Exchange, and strictly speaking a product like SQL server might be used for production as opposed to business purposes.
I would not use the term productivity software here as it is the least precise. To some extent, all software that is not specifically intended for entertainment (i.e. to kill time) would contribute to productivity (i.e. to save time), including the packages mentioned, but the term is applied to applications used commonly by a variety of workers in a variety of industries to enhance their day-to-day productivity. These would include general office software (e.g. word processors, contact managers) and role- or industry-specific software (e.g. accounting, process management). My smartphone app store has a "productivity" category but it certainly wouldn't be the place to buy SQL Server.
Middleware refers specifically to software that manages interaction between systems. Neither SharePoint nor SQL Server are middleware.
Solution 2:
They should be considered as Business Solutions Software, as is evident from the Microsoft website categorization.
Solution 3:
Microsoft calls them productivity tools. So do others in my experience. (If this were just a Microsoft question I would call it off-topic, but you seem to be asking more generally.)
(See Google results for "productivity tools microsoft.com".)
Solution 4:
The preferred term for discussing this kind of software tends to change every few years due to marketing pressures. Even though the core functions a business needs remain pretty static, the marketing wonks need a way to make the new versions seem new and exciting compared to the old ones that did pretty much the same thing.
So over the past couple of decades, "back office software", "enterprise software", "business solutions software", and "information systems software" have all had their heyday. And they all remain terms that would be readily recognized by someone familiar with the industry.
I'd tip my hat to either "enterprise software" or the aforementioned by Incognito "business solutions software" as the ones with the most "modern" connotation right now.
Solution 5:
Such software is commonly known as a service.
- SQL Server 2010 is a database service
- SharePoint 2010 is a SharePoint service
- Exchange 2010 is an Exchange service or an email service
They are characterised by how they tend to run in the background and are on a central server, not on an individual's computer - although I think SharePoint is the name for the client software as well as the service.