Exchange

You can run the following:

$userlist = Import-Csv C:\temp\sizes.csv
foreach ($user in $userlist){
Get-MailboxStatistics -Identity $user.samaccountname | select displayname, totalitemsize | Export-Csv c:\temp\results.csv
}

In your csv file name the column 'samaccountname'

Thanks TimGreen7077

I need further help

I am getting this error

in : Unexpected token 'in' in expression or statement.
    + CategoryInfo          : ParserError: (in:String) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : UnexpectedToken

[PS] C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Microsoft Exchange Server 2010>$userlist = Import-Csv "C:\spam\user.csv" foreach($user in $userlist){ Get-MailboxStatistics -Identity $user.SAMAccountName | select displayname, totalitemsize | Export-Csv "c:\spam\results.csv" }
in : Unexpected token 'in' in expression or statement.
    + CategoryInfo          : ParserError: (in:String) [], ParentContainsErrorRecordException
    + FullyQualifiedErrorId : UnexpectedToken

Did you copy the last sentence of Tim's script also?  That was instructional in nature and should not be run from the command line.  Here it is separated:

You can run the following:

$userlist = Import-Csv C:\temp\sizes.csv
foreach ($user in $userlist){
Get-MailboxStatistics -Identity $user.samaccountname | select displayname, totalitemsize | Export-Csv c:\temp\results.csv
}

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In your csv file name the column 'samaccountname'

Thanks @Jason for clarifying that for the user.

@Kaka tell me the name of your csv file and the version of exchange your are using and I will add it to the script for you.

Thanks Todd that worked just fine