"Also, the author is listed as gbarr, even listing all modules by author still doesn’t show Net::SMTP in his list."

Graham Barr (gbarr) was the original author. See "Net::SMTP - AUTHOR":

Graham Barr <gbarr@pobox.com>

Steve Hay <shay@cpan.org> is now maintaining libnet as of version 1.22_02

If you look at the top of the Net::SMTP page, you'll see a link to the author (Steve Hay), followed by a link to the distribution (libnet-3.10). That's standard at the top of all such pages:

Author Name > distibution-version > Module::Name