$ tar xzf gnupg-1.0.7.tar.gz
$ cd gnupg-1.0.7
gnupg-1.0.7$ ./configure
gnupg-1.0.7$ make
gnupg-1.0.7$ su
gnupg-1.0.7# make install

gpg --verify sendmail.8.11.6.tar.sig sendmail.8.11.6.tar.gz
gzip -dc sendmail.8.11.6.tar.gz | gpg --verify sendmail.8.11.6.tar.sig