Custom Alert Template

To customize alerts template:

   1. Create a working copy of AlertTemplates.xml. File Alerttemplates.xml
   is located at: Local_Drive\Program Files\Common Files\Microsoft Shared\Web
   Server Extensions\12\Template\XML directory.
   *Note* Do not modify Alerttemplates.xml itself. Make changes to a working
   copy.
   2. Edit the working copy that you just created.
   Use the stsadm command to read the changed templates into the database.
   STSADM -o updatealerttemplates -url -filename .
   3. Restart IIS.
   Note It may be necessary to restart SharePoint Timer Services.

To assign a custom alert template to a specific list:

Create a new custom template with a unique Name attribute in your working
copy of AlertTemplates.xml (You can copy paste the entire section with Name
SPAlertTemplateType.GenericList, change the name and modify the sections you
want to). Modify the template as necessary. After restarting IIS, write
object model code to set the list alert template.
SPAlertTemplateCollection ats = new
SPAlertTemplateCollection((SPWebService)(WebApplication.Parent)); //give
appropriate values for WebApplication
list.AlertTemplate = ats["name from above"];
list.Update();