-If you need to craete a bulk of users in exchange 2010/2007 , you will have to use the EMS

-The followin command will allow you to enter a password that will be common for all next created users
$Password=Read-Host “Enter Password” -AsSecureString

-Create a CSV file with the below header containning the requires infor for each user
Name,DisplayName,FirstName,LastName,Alias,UPN,OrganizationalUnit

-Run the below command and give him the path of the created CSV file
Import-Csv “CSV file path”|foreach {new-mailbox -Alias $_.Alias -FirstName $_.FirstName -LastName $_.lastName -UserPrincipalName $_.UPN -name $_.name -DisplayName $_.Displayname -OrganizationalUnit $_.OrganizationalUnit -ResetPasswordOnNextLogon $true -password $password}

-You will find all the users created divided randonly among availiable DB with password you provided in the first command with unlimited Quota