Outlook 2003 automatically displays error messages from the system tray when connectivity issues are detected. Unfortunately, when using mail servers off-site, these balloon tip error messages tend to appear excessively, even when there are actually no problems, proving them to be more of an annoyance than anything else.
You can stop these messages with a couple quick registry fixes:
Go to Start > Run and type regedit.
Navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Display Types\Balloons
Create three DWORD values named “Exchange”, “NetConn”, and “NetWarn”, all with the value of 0.
Close outlook and open it up again. If done correctly, balloon tip error messages will no longer pop up.