I'm pulling up the Global Address List from Outlook like so... Microsoft.Office.Interop.Outlook.Application oApp = new Microsoft.Office.Interop.Outlook.Application(); AddressList gal = oApp.Session.GetGlobalAddressList(); ...with the aim of eventually being able to search through this in my own application to retrieve contact information which I can then supply to a method that squirrels off an email. Unfortunately given that my own GAL has about 20K entries in (the customers much more) using a foreach or something simply doesn't work in an acceptable timeframe. I want to pass a string like "Tom" to a method and have it return a list of possible contacts. Is this possible outside of actually opening up Outlook and creating the mail there? Note: There are a couple of other questions similar to this but most seem to have no good answer. I'm hoping I have more luck.