The purpose of this files in this diretory is to provide a beacon for email viewing.

An image tag is embedded in an email, with a reference to a non-existinent CF page using
an encoded name - i.e. TrackingNNNNNxNNNNN.cfm  where the first set of Ns is the recipientId
and the second set of Ns are the token associated with the recipient id

The notfound.cfm template is installed in coldfusion to handle the template not found errors

If the "missing template" doesn't match the pattern above, it is ignored and a simple not found 
message is returned.