If the named message does not exist in the property files,
is rendered as "0".
Maybe the body of the tag was evaluated as an OGNL expression. ("e" minus "mail")
If the name exists in the property file like:
it is rendered as "e-mail".
This behavior is strange.
"If the named message is not found in a property file, then the body of the tag will be used as default message."
So a message in the body of the tag should be used as it is
like a message in the .properties file.