Powershell - Code help request

I have an existing posh script that's been working now I thought for a year.  However one step of it appears to be working but is not.. that's what Im wanting help with.

SO here's the script:

#Create-NewADUserO365.ps1
#3/3/15 Benjamin Hart, Unified Brands, Inc
#Created with Powershell ISE
#This powershell script will create a domain user object using a format of lastname, firstname, a SAM of first initial + last name
#It will also populate displayname, a default password, office and both proxyaddresses, the primary as used in your org and the 
#Dover required O365 one.  It will also verify the primary proxy address is not already used.
#With set-aduser you can alter almost any attribute of the user.

$theOU = read-host "Enter the OU name"
$Surname = read-Host "Enter the surname"
$GivenName = read-host "Enter first name"
$DisplayName = "$Surname, $GivenName"
$Password = "P@$$word1"
$name = $GivenName.substring(0,1)+$Surname
$proxyaddress = read-host "Enter the email address in full"


Import-Module activedirectory
# import-module servermanager



	#Edit the SearchBase to match your organization
	$myOU = Get-AdOrganizationalUnit -Filter "Name -eq '$theOU'" -Searchbase 'OU=People,DC=DIFC,DC=Root01,DC=org'
	

[b][u]while (Get-ADuser  -filter * -Properties ProxyAddresses|?{$_.proxyaddresses -contains $proxyaddress})
{
  $proxyaddress = read-host "$proxyaddress is already in use, please try another one"
}
Write-Host "$proxyaddress is not used yet."[/u][/b]


#Edit the below to match your domain(s)
$DoverProxyAddress = "$("smtp:")$($givenname.substring(0,1))$surname-$("unifiedbrands")-$("net")@dover.mail.onmicrosoft.com"
$Description = read-host "Enter persons description"
$jobtitle = read-host "Enter the Job Title"

#Edit the below to match your locations
$office = read-host "Enter the user's location, Michigan, Mississippi, Georgia, Oklahoma or Remote"

#Edit your locations if you choose to use this part
Switch ($Office)  {
    "Michigan" {
        $Street = "525 South Coldwater Rd."
        $City = "Weidman"
        $State = "Michigan"
        $Zip = "48898"
        $scriptpath = "\\domain\netlogon\milogin1.bat"
}
    "Mississippi"  {
        $Street = "1055 Mendell Davis Dr."
        $City = "Jackson"
        $State = "Mississippi"
        $Zip = "39272"
        $scriptpath = "\\domain\netlogon\adlogin.bat"
        }
    "Oklahoma"  {
        $Street = "4650 54th Street Maip Building 601"
        $City = "Pryor"
        $State = "Oklahoma"
        $Zip = "74361"
        $scriptpath = "\\domain\netlogon\oklogin.bat"
        }
    "Georgia"  {
        $Street = "2016 Gees Mill Rd. NE"
        $City = "Conyers"
        $State = "Georgia"
        $Zip = "30013"
}
}

$department = read-host "Enter the users Department"

New-ADUser -path $myOU -samaccountname $name -name $displayname -DisplayName $DisplayName -Surname $Surname -givenname $givenname -AccountPassword (ConvertTo-SecureString password -AsPlainText -force) -enabled:$false
set-aduser $name -emailaddress $proxyaddress -Description $Description -Title $jobtitle -Office $office -StreetAddress $Street -city $city -state $state -PostalCode $zip -UserPrincipalName $proxyaddress -ScriptPath $scriptpath -Department $department -Company "Unified Brands, Inc" -Country "US"

set-aduser $name -add @{proxyaddresses = "$("SMTP:")$proxyaddress"}
set-aduser $name -add @{ProxyAddresses = "$doverproxyaddress"}

 	
get-aduser $name 


pause

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The bold and underlined section is what is not working.  It should be checking to see if an smtp address is already in use, if so not letting me continue on, however yesterday was the first tie I had cause to create a domain user who would match an existing smtp address, but the script told me everything was fine and let me continue on.  It wasn't until the end where the New-Aduser came into play where it actually generated an error.