The advantages of autoconfiguration
So what exactly has happened here? If you've chosen to synchronize your email with Google, go ahead and launch the Mail application, which you'll find in the Dock. You have my permission to gasp when you see that a Gmail account now appears in Mail's list of accounts.
And that's the beauty of the Mail, Contacts & Calendars system preference. In the old days, you not only had to know a load of arcane settings (details such as email server addresses and ports, which I'll get to in a bit) but you also needed to configure multiple applications to put everything together. Now, in most cases, the Mac OS automatically takes care of those arcane settings and configures them in this single system preference. Adding even more accounts works much the same way: Click the plus button below the list of accounts, click a service, and fill in the appropriate fields.
Among the preconfigured services, a Microsoft Exchange account requires more steps than the others. In addition to knowing your username and password, you must also know the server address for your account. Since most Exchange accounts are created for business users, chances are good that the person who set you up with that account (someone working in the IT department, for example) can provide you with that information.
About the other services
While looking through the list of services, you'll notice that some are completely unrelated to mail, contacts, and calendars. Facebook and Twitter are for social networking, of course, and Flickr and Vimeo help you share pictures and video, respectively. So what are they doing here?
Mostly it's about tidiness. Sure, Apple could have added more preference panes to the System Preferences window and called them Social Networking and Media Sharing. But really, Mail, Contacts & Calendars is about the accounts you have--services you've registered with for which you need a username and password.
When you add Facebook and Twitter accounts, you have the ability to use those services within certain applications and the Notifications pane; likewise with Flickr and Vimeo. If you choose to share an image or video, adding Flickr and Vimeo makes the task easier since you can share that media directly from within a supported application.
Adding other accounts
For those of you who have screamed "But I have an account with Jo-Jo-E-Z-Does-It-Email.com! What am I supposed to do!?" as the drama of this lesson unfolded, calm yourself. Apple has done its level best to make configuring an email account simple, but it can't know the settings for each and every email service provider across the globe.
And because it can't, it provides the Add Other Account... entry, which gives you the opportunity to configure an account the old-fashioned way.
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