$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri http://ExServer123.com/PowerShell/ -Authentication Kerberos;
Import-PSSession $Session -AllowClobber;


Get-MailPublicFolder -ResultSize Unlimited | Get-ADPermission | Where-Object {
    ($_.ExtendedRights -Like "Send-As") -and ($_.IsInherited -eq $False) -and -not ($_.User -like "*S-1-5-21-*")} |
        Select Identity,User;

Get-MailPublicFolder |
    Select Alias,PrimarySmtpAddress,@{N="GrantSendOnBehalfTo";E={$_.GrantSendOnBehalfTo -join "|"}
    };