Random string showing up in exported CSV - powershell

Question

I have the powershell script built and I'm getting a "Random" bit of output into the CSV file. The string is MailboxExport(and a number). It looks like a value that (Get-MailboxExportRequest).name would return but I can't see where I would pull something like that or how it is being inserted. I think I may have just been staring at it too long and I may just need a fresh pair of eyes to spot my mistake. I would go into what the script is trying to do but I've put quite a few notes in the script that should explain it fairly well.
################################################## PST Extraction Script ##################################################
# Completed October 2013 by Trey Nuckolls
#
# This script is meant to extract PST files from the Site 1 Exchange server at the Site2 site and deliver those PST
# files to a share on the Site2 network. The script will change the input CSV file to keep track of which PSTfiles have been
# extracted and when that occoured. The script will also set security on the PST file so only the user and IT administraion
# can access the PST file.
#
# To run this script, enter the username of the Site 1 domain account that you want to target for extraction of a PST file then
# Run the script. Can be run from any machine on the network as long as it is run by someone with domain admin rights on the
# Site 2 network. Powershell v2 or v3 is required to run the script.
#
#############################################################################################################################
$InPstPath = '\\Site1_Server\PST_Store'
$OutPstPath = '\\Site2_Server\PST_Store'
$AdminPath = '\\Site2_Server\PST_Store\Admin\'
#Container for Site1 username
$User = Get-Content $AdminPath'login.txt'
#Container for encrypted Site1 Password
$PWord = Cat $AdminPath'pass.txt' | ConvertTo-SecureString
#Credential package for accessing Site1 resouces
$Credentials = New-Object –TypeName System.Management.Automation.PSCredential –ArgumentList $User, $PWord
#Creation of Powershell Drives for use during session
New-PSDrive -Name Site1Share -PSProvider FileSystem -Root $InPstPath -Credential $Credentials
New-PSDrive -Name Site2Share -PSProvider FileSystem -Root $OutPstPath
#Container for Powershell session to Exchange server
$PSSession = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri http://Site1_Server/powershell -Credential $Credentials
#Creation of Powershell session to Site1 Exchange server, including import of exchange commandlets
Import-PSSession $PSSession
#Import of the CSV file that lists users to be targeted
$In_List = Invoke-Command {Import-Csv "\\Site1_Server\PST_Store\To_Be_Exported.csv"} -computername Site1_Server -Credential $Credentials
$Processed = foreach ($objUser in $In_List) {
if ($objUser.Completed -ne "Yes") {
$TargetUser = $objUser.name
$ShortDate = (Get-Date).toshortdatestring()
$SourceFile = "Site1Share:\$TargetUser.pst"
$DestinationFile = "Site2Share:\$TargetUser.pst"
#Export Mailbox to PST File
New-MailboxExportRequest -Mailbox $TargetUser -Filepath $InPstPath\$TargetUser.pst
do {Start-Sleep -Seconds 10}
until((Get-MailboxExportRequest -Status InProgress).count -eq 0)
#Copy PST File to PST Share
Copy-Item -Path $SourceFile -Destination $DestinationFile
#Add Security access on PST file (Target_User-Modify). Domain Admin-Full is inherited from parent.
$Acl = Get-Acl $DestinationFile
$Permission = "Site2_Domain\$TargetUser","Modify","Allow"
$AccessRule = New-Object System.Security.AccessControl.FileSystemAccessRule $Permission
$Acl.SetAccessRule($AccessRule)
$Acl | Set-Acl $DestinationFile
#Remove PST file From Temporary area
Remove-Item -Path $SourceFile -Force
#Write back to checklist for new items that have just been processed
[PSCustomObject]#{Name=$TargetUser;Completed="Yes";Date=$ShortDate}
} else { if ($objUser.Completed -eq "Yes") {
#Passthrough of items that have already been completed
[PSCustomObject]#{Name=$objUser.name;Completed=$objUser.Completed;Date=$objUser.Date}}
}}
#Output the new version of the checklist
$Processed | export-csv -Path C:\TEMP\processed.csv
#Overwrite the old version checklist with the new one
Move-Item -Path C:\TEMP\processed.csv -Destination Site1Share:\To_Be_Exported.csv -force
#Cleanup PsDrives and PsSessions
Remove-PSDrive -Name Site1Share
Remove-PSDrive -Name Site2Share
Remove-PSSession -Session (Get-PSSession)
Input CSV is...
"Name","Completed","Date"
"User1","Yes","10/8/2013"
"User2","Yes","10/11/2013"
"User3",,
and output is...
"Name","Completed","Date"
"User1","Yes","10/8/2013"
"User2","Yes","10/11/2013"
"MailboxExport7",,
"User3","Yes","10/11/2013"

Answer 1

It is indeed very likely that the issue is caused by New-MailboxExportRequest, as you already suspected. The cmdlet prints information about the created object, which lumped together with the rest of the output you create in the loop, and then assigned to the variable $Processed.
To avoid this you can suppress the cmdlet output like this:
New-MailboxExportRequest -Mailbox ... | Out-Null
or like this:
New-MailboxExportRequest -Mailbox ... >$null
Assigning the output to a variable should work as well:
$exportRequest = New-MailboxExportRequest -Mailbox ...

Answer 2

On you Export-CSV, try adding the flag: "-NoTypeInformation"

Answer 3

I think this may be some sort of name space crossover issue between the custom object and another existing object (probably the mailboxexportrequest object on the exchange server). After messing around with this for a while I was able to get it to fail in a new way where the resultant csv file was full of details from the mailbox exports and their was a 'name' column that also had listed the usernames. I changed the hashes on the input csv from 'name to 'username' and the resultant MailboxExport entries have ceased. There are now blank row but I'm certainly willing to live with that imperfection as it doesn't break this (short lived) process.
If anyone has any insight into the root cause I'd certainly love to hear what it is but I think I've figured out a solution to the point that I can live with.