Reforming the Group

When sending invitations to emails for people who I thought were probably in the original email list, I discovered I did not have good email addresses for everybody in my Outlook list, etc. Some people have changed addresses since I put them into my Outlook or in my webmail address book. Anyway, it is going to be tough to get the whole list reconstructed if it is just me working on it. Please help! There are all kinds of good reasons to get some better communication set up. Thanks!