Remove E-Mail address with Specific Domain Name in Microsoft Exchange 2010

Function Remove-OSCEXEmailAddress 
{ 
    [CmdletBinding(SupportsShouldProcess=$true)] 
    Param 
    ( 
        #Define parameters 
        [Parameter(Mandatory=$true,Position=1)] 
        [string]$Filter, 
        [Parameter(Mandatory=$true,Position=2)] 
        [string[]]$DomainName 
    ) 
    Process 
    { 
        #Get mailboxes or distribution groups 
        $recipients = Get-Recipient -Filter $Filter -ResultSize unlimited -Verbose:$false 
        if ($recipients -ne $null) { 
            foreach ($recipient in $recipients) {         
                if ($recipient.RecipientType -notmatch "UserMailbox|DistributionGroup") { 
                    $warningMsg = $Messages.RecipientTypeIsNotSupported 
                    $warningMsg = $warningMsg -replace "Placeholder01",$($recipient.RecipientType) 
                    $pscmdlet.WriteWarning($warningMsg)                 
                } else { 
                    for ($i=0;$i -lt $recipient.EmailAddresses.Count;$i++) { 
                        #Begin to remove invalid email address one by one. 
                        $addressDomain = $recipient.EmailAddresses[$i].AddressString.Split("@")[1] 
                        if ($DomainName -contains $addressDomain) { 
                            $primarySmtpAddress = $recipient.PrimarySmtpAddress.ToString() 
                            $invalidEmailAddress = $($recipient.EmailAddresses[$i]) 
                            #Use ShouldProcess method for supporting -Whatif parameter 
                            if ($pscmdlet.ShouldProcess($($recipient.Alias))) { 
                                if ($invalidEmailAddress -ne $primarySmtpAddress) { 
                                    $verboseMsg = $Messages.RemoveAddress 
                                    $verboseMsg = $verboseMsg -replace "Placeholder01",$($recipient.EmailAddresses[$i]) 
                                    $pscmdlet.WriteVerbose($verboseMsg) 
                                    Switch ($recipient.RecipientType) { 
                                        "UserMailbox" { 
                                            $mailbox = Get-Mailbox -Identity $($recipient.Alias) -Verbose:$false 
                                            $returnValue = $mailbox.EmailAddresses.Remove($invalidEmailAddress) 
                                            if ($returnValue) { 
                                                Set-Mailbox -Identity $mailbox -EmailAddresses $mailbox.EmailAddresses -Verbose:$false 
                                            } 
                                        } 
                                        "MailUniversalDistributionGroup" { 
                                            $distributionGroup = Get-DistributionGroup -Identity $($recipient.Alias) -Verbose:$false 
                                            $returnValue = $distributionGroup.EmailAddresses.Remove($invalidEmailAddress) 
                                            if ($returnValue) {  
                                                Set-DistributionGroup -Identity $distributionGroup -EmailAddresses $distributionGroup.EmailAddresses -Verbose:$false                                     
                                            } 
                                        } 
                                        "DynamicDistributionGroup" { 
                                            $dynamicDistributionGroup = Get-DynamicDistributionGroup -Identity $($recipient.Alias) -Verbose:$false 
                                            $returnValue = $dynamicDistributionGroup.EmailAddresses.Remove($invalidEmailAddress) 
                                            if ($returnValue) { 
                                                Set-DynamicDistributionGroup -Identity $dynamicDistributionGroup -EmailAddresses $dynamicDistributionGroup.EmailAddresses -Verbose:$false                                     
                                            } 
                                        } 
                                    } 
                                } else { 
                                    #Remove primary SMTP address is not supported by this function. 
                                } 
                            } 
                        } 
                    } 
                } 
            } 
        } else { 
            $errorMsg = $Messages.CannotFindRecipient 
            $customError = New-OSCPSCustomErrorRecord ` 
            -ExceptionString $errorMsg ` 
            -ErrorCategory NotSpecified -ErrorID 1 -TargetObject $pscmdlet 
            $pscmdlet.WriteError($customError) 
            return $null 
        } 
    } 
}