It has been reported that the Maven enforcer plugin complains with the latest Simple Java Mail version, as the transitive dependency rfc2822-validator depends on an older javax.mail version.
Currently, to work around this you need to make rfc282-validator non-transitive and then an exclusion for javax.mail, not exaclty pretty.
I've patched rfc282-validator to be able to deal with a version-range so that Maven can resolve the version properly to whatever Simple Java Mail indicates.