If you look at what Linux users are actually using, there are 8 to 10 different email programs for the examples given above. This is true for most server functions. The applications are not what matters, in systems with a high security system, such as SE Linux. There, the malware cannot spread.
I might agree with you that Ubuntu is not nearly as secure as it might be, but even then, as the most popular Linux version, it is nearly unheard of to find a virus problem. Plus, the Red Hat commercial systems probably transmit and transfer more money each day than Obama's deficit. If there is a target that criminals would want to pick, Linux should be it. But breaks on these systems are rare. When they do happen, it usually turns to involve someone on the inside.
From this, I wind up thinking that the Mac isn't as secure as Linux, and it may soon be less secure than Windows.
But the Linux email programs are usually small and open. What this means is that once an exploit is found, it is plugged, often the same day it is reported.
Apple is still using the old Microsoft trick of just pretending that exploits don't exist unless they are acknowledged. Microsoft has abandoned this as it only made people trust them less. maybe the recent fuss about that Russian worm will have the same result on Apple.
Given that, I would seriously recommend that you look carefully before deploying Apple products in any environment which actually requires security. The truth is that Apple computers and Apple phones have already been broken several different ways. Not as much has happened with Linux based computers and phones. I am not aware of breaks at a more than theoretical level on the new Windows Phones, though there is a lot of action on Windows 7. Windows continues to be the major platform that needs the patch up of antivirus programs.
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