my $mailfrom = 'someone@somewhere.com';
my $mailcommand = "/usr/lib/sendmail -f\"$mailfrom\" -O\"NoRecipientAction=add-to\" -t ";

my $to = '...' # recipient goes here

open MAIL, "| $mailcommand $to" or die "$0: Cannot execute command: $!\n";

print MAIL <<EOT;
To: $to
MIME-Version: 1.0
Content-Type: text/html
Content-Transfer-Encoding: 8Bit
Subject: Some subject here

... your text ...

EOT
close MAIL;