Messages for Mac: Set up iMessage
You can send unlimited messages to friends who use iPhone, iPad, iPod touch, and Mac with iMessage.
For iMessage, you need an Apple ID. If you set up an iTunes or iCloud account, you already have an Apple ID. If you don’t have an Apple ID, you can create one in Messages.
If you have a message account with Google Talk, Jabber, or Yahoo!, you can add these to Messages too. See Set up other Internet accounts.
Set up iMessage
Choose Messages > Preferences, click Accounts, then select iMessage in the Accounts list.
Enter your Apple ID and password, then click Sign in.
If you forgot your password or Apple ID, go to your Apple ID account page, select “Forgot Apple ID or password?” then follow the instructions.
After signing in, do any the following:
Specify the email addresses and phone numbers that receive messages: Click Add Email, then enter email addresses. Select the email addresses and phone numbers you want to use to receive messages.
If you have a phone number associated with your Apple ID, it is automatically added to the list. When you set up your iPhone to use your Apple ID, your phone number is associated with your Apple ID.
Have others notified when you have read their messages: Select “Send read receipts.” If you enable read receipts, people who send you messages will see when you’ve read them.
You can also send read receipts for a conversation only.
Stop using iMessage
If you don’t want to see messages from iMessage on your Mac, you can turn off iMessage using iCloud preferences.
Choose Apple menu > System Preferences, click iCloud, then click the Options button next to iCloud Drive.
Deselect Messages in the list of apps, then click Done.
WARNING: Turning off individual iCloud features can remove data stored in your apps. Before the feature is turned off, you’re asked whether you want to keep a copy of the data.
If you have an iPhone with iOS 8.1 or later, you can also send SMS messages to any mobile phone from your Mac. See Set up your iPhone for SMS text messages on your Mac.