SMTP Relay to a Hub server with the Mailbox servers down... Anonymous email?

Question

I'm trying to send anonymous email to an outside email address from inside, with the Mailbox servers down. We are using cmdlets to relay to the Hub Transport server, but the error "Mailbox Unavailable" keeps coming back. I've tried multiple methods
of powershell SMTP email delivery, and the errors are virtually identical.
Does anyone have any methods to deliver anonymous email to a relay server while the Mailbox servers are down?
PS D:\#E2010-Management> #####Script1 - Set Password
$s = New-Object System.Security.SecureString
$credential = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList "NT AUTHORITY\ANONYMOUS LOGON", $s
#####Script2 - Send Email
$From = "[email protected]"
$To = "[email protected]"
$SMTPServer = "SMTPSERVER.company.com"
$SMTPPort = "25"
$subject = "test"
$body = "n"
$smtp = New-Object System.Net.Mail.SmtpClient($SMTPServer, $SMTPPort);
$smtp.EnableSSL = $false
$smtp.Credentials = New-Object System.Net.NetworkCredential($credential.GetNetworkCredential().Username, $credential.GetNetworkCredential().Password)
$smtp.Send($From, $To, $subject, $body);
Exception calling "Send" with "4" argument(s): "Mailbox unavailable. The server response was: 5.7.1 Unable to relay"
At line:15 char:11
+ $smtp.Send <<<< ($From, $To, $subject, $body);
+ CategoryInfo : NotSpecified: (:) [], MethodInvocationException
+ FullyQualifiedErrorId : DotNetMethodExceptionPS D:\#E2010-Management> $s = New-Object System.Security.SecureString
$creds = New-Object -TypeName System.Management.Automation.PSCredential -ArgumentList "NT AUTHORITY\ANONYMOUS LOGON", $s
$creds.GetNetworkCredential()
$smtp.EnableSsl = $false
Send-MailMessage -to "[email protected]" -from "[email protected]" -subject "test" -SmtpServer "SMTPRELAY.company.com" -credential $creds
UserName Password Domain
ANONYMOUS LOGON NT AUTHORITY
Send-MailMessage : Mailbox unavailable. The server response was: 5.7.1 Unable to relay
At line:5 char:17
+ Send-MailMessage <<<< -to "[email protected]" -from "[email protected]" -subject "test" -SmtpServer "SMTPRELAY.company.com"
-credential $creds
+ CategoryInfo : InvalidOperation: (System.Net.Mail.SmtpClient:SmtpClient) [Send-MailMessage], SmtpFailedRecipientException
+ FullyQualifiedErrorId : SmtpException,Microsoft.PowerShell.Commands.SendMailMessage

Answer 1

Hi Mr.Cross,
If you want to allow anonymous relay, you need to create a new Receive connector on the Hub Transport server and use the Shell to grant the relay permission to anonymous connections.
Here’s an article for your reference:
Allow Anonymous Relay on a Receive Connector
http://technet.microsoft.com/en-us/library/bb232021(v=exchg.141).aspx
Notes:
Allowing anonymous relay on a Receive connector is a security risk, especially on Internet-facing servers.
If you have any further questions, please do not hesitate to post back.
Best regards,
Eric