I can't see how mailing 100+ messages individually is going to be any different from using mail merge to mail 100+ messages?
http://www.gmayor.com/ManyToOne.htm in one to one mode will allow you to merge to e-mail with personalised messages - even different subjects if you wish, or you could merge as an attachment with or without a personalised covering message.
The only proviso is that the data source must be an Excel worksheet.
However you can create a message in Outlook and save the message as a template and create 100+ separate messages from that template if you have the time and inclination.
The following macro run from a button on the ribbon or QAT (Quick Access Toolbar) or keyboard shortcut will open a new message using whatever you have saved as the template as its basis. Change the file path and template name as appropriate.
Code:
Sub CreateFromTemplate()
Dim olItem As Outlook.MailItem
Set olItem = Outlook.CreateItemFromTemplate("C:\Path\My Template Name.oft")
olItem.Display
lbl_Exit:
Set olItem = Nothing
Exit Sub
End Sub