Powershell - Organizer Email Address - powershell

Question

I'm trying to retrieve the email address of the Organizer of a meeting in MS Exchange 2010, using Powershell.
(Get-Mailbox -Identity "John Doe").PrimarySmtpAddress
I get the below error
The operation couldn't be performed because object 'John Doe' couldn't be found on 'xxxxxxxxxxxxxx'
These are for meetings that have just been created, so how can the Organizer not exist?
Edit:
Here's the sequence of events:
Fetch list of calendar events from exchange within specific date range
Fetch email address of Organizer for each event <-- this is where I'm stuck
Full script:
$credential = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList $username,$password
$session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri http://xxxxxxxxxxxxxxx/PowerShell -Authentication kerberos -Credential $credential
Import-PSSession -Session $session -DisableNameChecking
#Date ranges
$exportDate = Get-Date -Format d
$startTime = (Get-Date).AddDays(-1)
$endTime = (Get-Date).AddDays(+1)
$app = New-Object -ComObject Outlook.Application
$ns = $app.GetNamespace('MAPI')
$calFolder = 9
$calItems = $ns.GetDefaultFolder($calFolder).Items
$calItems.Sort("[Start]")
$calItems.IncludeRecurrences = $true
$dateRange = "[Start] >= '{0}' AND [End] <= '{1}'" -f $startTime.ToString("g"), $endTime.ToString("g")
$calExport = $calItems.Restrict($dateRange)
$exportFile = "D:\file.csv"
$calExport | select Subject, StartInStartTimeZone, EndInEndTimeZone, Duration, Organizer, RequiredAttendees, OptionalAttendees, Location | sort StartUTC -Descending | Export-Csv $exportFile
$exportData = Import-Csv $exportFile
foreach ($line in $exportData)
{
$emailAddress = $line.Organizer
$emailAddress = (Get-Mailbox -Identity $line.Organizer).PrimarySmtpAddress
$line | Add-Member -Membertype Noteproperty -Name OrganizerEmail -Value $emailAddress
[array]$csvData += $line
$emailAddress = $null
}
Remove-PSSession $session
Please assist!

Answer 1

Here's what I used to get the Organizers email address
Get-ADUser -Filter {SamAccountName -like "*John Doe*"}