First off, i agree with /\/\averick that calling sendmail directly is risky, but if you must do such things (e.g. prod machine and modules cannot be installed with out internal QA :-( ), sendmail will take multiple addresses (untested code ahead):

my $local_addr = 'some@addr.com';
my @addrs = qw(mzsanford@cpan.org foo@perl.com joe@cool.com);
my $mail_string = join(',',@addrs);
open(MAIL,"| /usr/lib/sendmail -t") || die "fork() : $!\n";
print MAIL "From: $local_addr\n";
print MAIL "To: $local_addr\n";
print MAIL "Bcc: $mail_string\n\n";
print MAIL "Subject: hello\n";
print MAIL "foo, bar, and the like.\n";
print MAIL "\n.\n";
close(MAIL) || die "close() : $!\n";
[download]

... but i am not sure, and my unix box is down at the moment so i can't test. Also, they will get a mail from you, to you, and BCC'd to them ... common spammer stuff ... i even have a filter for it.

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_{can't sleep clawns will eat me}
-- MZSanford