Yes that process will clear all of the email auto-complete entries. Auto-complete should function normally (and you should be able to delete entries as normal) once this is done. I say "should", because there's really no guarantees, but it has worked for me in the past.

It's like I tell some of my clients: A lot of people tend to use the auto-complete cache as a de facto contact list, but it really wasn't made for that purpose. The cache does tend to get corrupt from time to time. This is particularly problematic in an Exchange environment, because when people move between OUs they can suddenly find themselves getting NDRs due to the auto-complete trying to resolve an address that doesn't exist anymore. Bottom line is: if an email address is important to you, make a real contact out of it.

Sorry for the slight deviation from topic, there.

-SW