'Guidelines sent via CD' versus 'Guidelines sent in a CD'

[Tom]

Hi

Could you please tell me which of the following is more natural and correct?

[Mister Micawber]

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#2 is more businesslike.
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Native English teacher at Mister Micawber's

[Yankee]

Hi Tom

How about this as an alternative:

I hope you are following the guidelines provided in the CD.
.
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"Nearly all men can stand adversity, but if you want to test a man's character, give him power." ~ Abraham Lincoln