Mac can't connect to IMessage?

There are users who have recently encountered a strange thing-in any case not connected to the iMessage (that is, the "information" app in the Mac), and other Macs in the same network environment can connect, re-installed after the system is not resolved.

Originally, the culprit is that the MAC has no serial number. Someone might ask, how does a Mac with no serial number exist? He just caught up. Sometimes, the serial number is lost after the motherboard has been replaced by some imac at a time.

The IMAC, which doesn't have a serial number, has been working all the time, and even until recently, the Info app worked. Later he sent the computer to Apple after the sale, the customer service personnel with an "Apple Authorized Service Provider" software, to the MAC to re-write the original serial Number (box label on the serial number), the problem is immediately resolved.

As to what the problem is, no one seems to be able to say it clearly. However, the customer service still gives a few possibilities:

Maybe it's a new feature of the IMessage protocol or the "messaging" app that allows them to work only on Macs with the correct serial numbers; If so, then this may be one way Apple can fight "black apples";

Another possibility is that IMessage initially did not plan to support the MAC without serial number, but only recently began to enforce; a Bug that recently appeared is not impossible;

In summary, if your Mac is always unable to connect to the "info" app, you might want to see if it doesn't have a serial number. If it does not, then there seems to be no good way apart from the delivery of repair.