All reports of maintainer-address-is-on-localhost for the archive. The extended description of this tag is:

The maintainer address includes localhost(.localdomain), which is an invalid e-mail address.

Refer to Debian Policy Manual section 5.6.2 (Maintainer) for details.

Severity: serious, Certainty: certain

Check: fields, Type: binary, udeb, source

This tag has not been emitted in any package tested by Lintian.