Hi Can any one help mewhat is default size of the Exchange mailbox stores in 2000 and 2003 and 2007 std and ent . And also maximum number of stores can be configured on each server.

Here ya go: E2K Standard - 16GB / One store per server E2K Enterprise - 8TB / 20 stores per server E2K3 Standard - 16GB / One store per server E2K3 Enterprise - 8TB / 20 stores per server E2K3 SP1 Standard - 18GB but can be raised to up to 75GB via Registry key / One Store per server E2K7 Standard - 50GB default per store, but can be unlimited with Registry key / 5 stores per server E2K7 Enterprise - 16TB per store / 50 stores per server Hope this helps!