Email alerts not sent from SharePoint Portal Server 2003

Recently I ran into a problem with SharePoint Portal Server 2003: email alerts are not sent from any alerts created on any lists in the portal. Users still can see alert results under "My Alerts" on their personal sites. However, email alerts are sent if alerts are created on a list in a WSS site.

The situation is similar to the issue described in Jopx's blog. However, the hotfix mentioned in that blog post is obsolete now, since the described problem was addressed by SharePoint Portal 2003 Service Pack 2.

Unfortunately, even SP2003 SP2 does not remove the problem that I faced.

After several desperate experiments, a surprisingly simple solution popped up. SharePoint Alert and SharePoint Timer services must use a domain account. This is necessary even when I have a local database in a single server deployment.

The true reason behind this is that these services need to contact Active Directory for security issues. When a user browses to his/her My Site, the site owner was already authenticated so the alert results show up properly. However, before sending out alert emails, SP2003 services need to make sure that the receiver already has enough authorization to see the alert results. Hence at least read-access to Active Directory is required, whereas a local system account can't satisfy.

You can read more about discussions around this issue in this forum thread.

The moral here is that many things might be quite complicated although they appear simple. Furthermore, single server deployment of SharePoint 2003 in production environment may not be in common, so a quick search with Google would not yield the required answer.