Mail templates in Microsoft Entourage
There is no specific mail template feature built-in to Microsoft Entourage v.X or 2004. However, you can make use of some other features to get similar effects.
Signatures
If you need to store boilerplate text, you can put it in a signature. Then, you can re-use it by selecting that signature for use with a new message.
To edit signatures in Microsoft Entourage, select "Signatures" from the Tools menu.
This tip works in Microsoft Entourage v.X and 2004.
HTML mail
This tip requires Microsoft Office 2004, with Entourage 2004 and Word 2004.
If you with to have rich text or HTML formatting, you can create your source documents in Word. Then, use the "Send To (HTML)" feature in the File menu of Microsoft Word 2004 to open the formatted message in Entourage 2004.
Because your source Word documents can be saved as Word documents, you can re-open them to re-use them. This serves much the same purpose as having a template, although the "template," in this case, is not directly accessible in Entourage.
If you need to make changes to the rich text message, you will need to make those changes in Word 2004 and then use the "Send To (HTML)" command again, which creates another new mail message. Close -- and don't save -- the previous message (the one that required changes).