Opening Mail files in container fields

Hello

If I put a JPG file in a container field, and then run a script which Exports the field contents, with the 'automatically open file' option ticked, the stored file opens up in Preview. If I do the same thing with a Mail email file, it opens up in TextEdit.

I'm wondering whether it is possible to specify the application in which a file is opened, depending on the filename. i.e.

'If the file you've just exported, ends in .doc, open it in Word; if it ends in .jpg, open it in Preview; if it ends in .eml, open it in Mail'

Don't suppose anyone knows how to do that?

Thanks