Thank you for your comments.

#!/usr/local/bin/perl
$mailprog = '/usr/sbin/sendmail';
 $recipient = 'charley@aug.com';
 print "Content-type: text/html\n\n";
 print "<Head><Title>Thank you!</Title></Head>";
 print "<Body><H1>Thank you for your comments.</H1>";
 print "<A HREF=http://www.oldcity.com/~charley/index.html> Go Back</A>"; 
 read(STDIN, $buffer, $ENV{'CONTENT_LENGTH'});
 @pairs = split(/&/, $buffer);
 foreach $pair (@pairs)
{
    ($name, $value) = split(/=/, $pair);
     $value =~ tr/+/ /;
    $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
    # $value =~ s/~!/ ~!/g;
     # print "Setting $name to $value<P>";
    $FORM{$name} = $value;
}
 open (MAIL, "|$mailprog -f $FORM{'username'} $FORM{'recipient'}") || die ;
 print MAIL "From: $FORM{'username'} ($FORM{'realname'})\n";
 print MAIL "Subject: Mail from $FORM{'username'} ($FORM{'realname'})\n";
 print MAIL "$FORM{'username'} ($FORM{'realname'}) sent the following\n\n";
 print MAIL  "------------------------------------------------------------\n";
 print MAIL "$FORM{'comments'}";
 print MAIL "\n------------------------------------------------------------\n";
 print MAIL "Server protocol: $ENV{'SERVER_PROTOCOL'}\n";
 print MAIL "Remote host: $ENV{'REMOTE_HOST'}\n";
 print MAIL "Remote IP address: $ENV{'REMOTE_ADDR'}\n";
 close (MAIL);