Additionally, you can set a registry key to configure the automatic retry interval in this scenario.  Follow these instructions using regedit:

1. Open a registry editor, such as Regedit.exe or Regedt32.exe.
2. Navigate to: HKLM\System\CurrentControlSet\Services\SMTPSvc.
3. Right-click SMTPSvc and select New | Key.
4. Name the new key Queuing.
5. Right-click Queuing and select New | DWORD Value.
6. Name the new DWORD value GlitchRetrySeconds.
7. Double-click GlitchRetrySeconds to edit its value data.
8. Change the Base to Decimal.
9. In the Value data field, enter the number of seconds that Exchange Server 2003 should wait before attempting to resend a message.
10. Click OK to save the change, and then close the Registry Editor.
11. Restart the Simple Mail Transfer Protocol (SMTP) service for the change to take effect.