Random Alerts

We are on Winsows Server 2003 / Exchange 2003 / single domain less than 100 users.  One mail server.  We have been using BE version 12.0 and recently upgraded to 12.5. We are experiencing the same problem with both versions.

We are using MAPI email alerts; simple alerts to inform us of whether the job succeeded or failed.  We are not including the job log in the alerts.  For some reason beyond me, the alerts will work fine for a few days or sometimes weeks, and then they just stop working.  Usually rebooting the server will fix it for a few days (or sometimes weeks), but then the problem keeps resurfacing.  We have all the latest updates installed for Windows and Backup Exec.  We use Outlook 2003 for the client and XP Pro SP3 on our workstations.

Thanks in advance for any help!