Cannot send email from Powershell on Mailbox Role

Hi,

I am trying to send an email from Powershell on Mailbox role of Exchange server. I have installed Symantec Mail Security on Mailbox Role.

When I try to send email using Powershell, I got the following error.

PS C:\a> Send-MailMessage -to admin@domain.com -Subject "Alert Closed.. Service is restarted on Computer" -fromAdmin@domain.com -Body "The service was found stopped on Computer it was started automatically and it is now running normally." -bodyasHTML -priority High -SmtpServer smtp.domain.com
Send-MailMessage : Service not available, closing transmission channel. The server response was: 4.3.2 Service not active
At line:1 char:1
+ Send-MailMessage -to admin@domain.com -Subject "Alert Closed.. Service is ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (System.Net.Mail.SmtpClient:SmtpClient) [Send-MailMessage], SmtpException
    + FullyQualifiedErrorId : SmtpException,Microsoft.PowerShell.Commands.SendMailMessage

This command is working fine on every server except exchange server (CAS, Mailbox). Firewall is off on the servers.

Any help will be highly appreciated.

Regards,

Anees