Q: Messages Not Delivering

Might be a corrupt .plist.

Do a backup, preferably 2 backups on 2 separate drives.

Quit the application.

Go to Finder and select your user/home folder. With that Finder window as the front window, either select Finder/View/Show View options or go command - J.  When the View options opens, check ’Show Library Folder’. That should make your user library folder visible in your user/home folder.  Select Library. Then go to Preferences/com.apple.iChat.plist.  Move the .plist to your desktop.

Restart the computer, open the application and test. If it works okay, delete the plist from the desktop.

If the application is the same, return the .plist to where you got it from, overwriting the newer one.

If that doesn’t work, repeat the above but delete the com.apple.imagent.plist

Thanks to leonie and Ralph Johns (UK) for some information contained in this.

Hi,

It might be that your iMessages Account is not logged in properly.

One reason for this can be the Serial Number is missing from the Logic/mother board (normally not put on when the board is replaced or refurbished)

You can check by going to the Apple Icon Menu and selecting About this Mac.

In the panel that shows up click on the line that tells you the OS you are using (OS X 10.8.x in Mavericks case).

This will tell you the build number (Another way that Apple counts the OS versions).

Clicking that will then show you the Serial Number.

Yosemite and El Capitan have different panels and it show in the Front "page" of Overview

If it is missing you will need to visit an Apple Store and have it put on your computer.

If that is too far try an Apple Authorised Service Provider (AASP)

9:38 pm      Monday; March 7, 2016