Which are the most appropriate salutations in the following situations? You have TWO choices.

Invitation to an in-company Christmas party
Dear colleagues,
Dear all,
Dear employees of the company,
Dear invitees to the Christmas party,
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Notice of a board meeting
Most respectable directors,
Dear board members,
Dear Sirs,
Dear all on board with me,
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The Director of the Tax Administration
Dear Mr. Smith,
Dear Smith,
Dear John,
Dear Director Smith,
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Parliamentary commissioner for minority rights
John Smith, Commissiner,
Dear Mr. Smith,
Commissioner Mr. Smith,
Dear Commissioner Smith,
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Director of the Environmental Agency
Dear Sir,
Dear Director Smith,
Director John Smith,
Dear Sir Director,
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The users of the printer in the office
Dear colleagues,
Printing notice:
Dear Printers,
Dear Co-users,
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A lawyer, your opponent in a lawsuit
Dear Mr. Peter,
Dear Mr. Schmidt,
Dear Mr. Attorney,
Dear Sir,
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The dean of your educational insitution
Dear Dean Cramer,
Respecable Dean Cramer,
Dear Cramer,
Dear Mr. Cramer,
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