In a business environment, when writing to a colleague or partner, the practice in an "egalitarian tradition" has allowed it appropriate not to have any greeting but addressing the person directly.
The form of respect appropriate for this "egalitarian tradition" allows for prefixes such as Mr, Ms, Dr.
For example, writing to your senior director,
I wish to inquire about the status of the new production line, which will be assembling our new design of the product.
Tomorrow is the deadline for submission of projects for the next quarter. My dept is aware of your plans to implement the XYZ initiative this coming quarter. However, I am unable to locate the plans that your team may have submitted.
We may have situational or contextual declarations when addressing colleagues, especially to a group of colleagues.
Congratulations John, and your team,
for achieving the 2015 goal of ...
Happy new year esteemed colleagues,
HR is elated to announce our reaching a new agreement with the 999th union.
To a colleague who does not outrank you significantly, or who is lesser in rank,
How are you Susan?
I hope you are all refreshed from your brief assignment at our Chicago office. Is it really windy up there? I am wondering when we might get a glance at the design finalized during your 2 week stint there.
Good morning Dr Goodnite,
As you requested yesterday, these are the reports you requested me to request from the team supervisors.
To your supervisor, or team leader
May I drop by your office before lunch to pick up my bonus check?
To your chummy colleague,
It's 12 o'clock - lunchtime! We had plans to the mall, remember?!!