There are still people using 2003 as I found out. While helping convert from 2003 to a web based email solution for Exchange, I needed to export a full list of email addresses. I was searching for a while on Google before I found a quick and easy way to export the list.
ldifde -d "DC=domain,DC=com" -r "(&(mailnickname=*))" -l proxyAddresses -f emailaddresses.txt
-d set the domain you are connecting to
-r set the filter for the query
-l set the query to list the attribute(s) you are looking for
-f tells the query to write to the following filename