My organization has (had) an email retention policy of 30 days for
email and 365 days for appointments.

We have been on legal hold for the last 3 years so I am looking at
roughly that amount of data that will need to be removed when we get
the green light to come off of hold from the legal folks. (I'm told
that is coming soon)

My question is how does the expire/reduce run most efficiently? Should
I just set my 30/365 days settings and let it run or does it run more
effiently (quickly) if I did something like 365/720 then stepped down
to the 30/365, which would require 2 passes through the post office.

I know from observing the initial implementation of the policy, it is
going to take more than a week to get everthing down to size. Also, I
will probably have to run this stand alone so I can start/stop it as
needed. We can't take too much of performance hit if I just start it
from the server and let it run.

Once I get the post office trimmed down, I'll be re-enabling the
nightly scheduled expire/reduce options for maintenence.

Any advice or recommendations are appreciated.