Consider $subject. The first time into the loop, it might read  [name]! You can enlarge your whatever! Then you swap in a name, and send the first email.

So what is $subject going to be the second time through the loop?

  Aaron Anderson! You can enlarge your whatever!
[download]

It looks like you need to make copies of both $subject and $messages each trip through the loop, and expand macros in the copies.

You might want to learn a templating module, rather then rolling your own, and using CGI's ugly HTML-generating code. (Perl should look like Perl, and HTML should look like HTML.) In specific, I recommend Text::Template as being very easy to learn.

#!/usr/bin/perl -w

open (STDERR, ">>/home/sulfericacid/public_html/test/error.log")
   or die "Cannot open error log, weird...an error opening an error lo
+g: $!";
   
use strict;
use warnings;
use POSIX;
use CGI qw/:standard/;
require SDBM_File;

my %sig;
my %emails;
my $editsig;
my $sigsave   = "sig.dbm";
my $lock      = "pass";    #password
my $list      = "list.dbm";
my $adminmail = "admin\@test.com";
my $sendmail  = "/usr/lib/sendmail";
my $unsub     = "http://sulfericacid.perlmonk.org/test/how.pl";  # uns
+ub link

tie %emails, 'SDBM_File', $list, O_CREAT | O_RDWR, 0644;
if ( !tied %emails ) {
    print "database unsuccessful $!.\n";
}

tie %sig, 'SDBM_File', $sigsave, O_CREAT | O_RDWR, 0644;
if ( !tied %sig ) {
    print "database unsuccessful $!.\n";
}

print header, start_html('Email Management');

print start_form(), table(
    Tr(
        td("Subject: "),
        td(
            textfield(
                -name => 'subject',
                -size => 40
            )
        )
    ),
    Tr(
        td("Message: "),
        td(
            textarea(
                -name    => 'message',
                -columns => 40,
                -rows    => 5
            )
        )
    ),
    Tr(
        td("Signature: "),
        td(
            textarea(
                -name    => 'signature',
                -default => $sig{'default'},
                -columns => 40,
                -rows    => 5
            )
        )
    ),
    Tr(
        td("Password: "),
        td(
            password_field(
                -name    => 'password',
                -size    => 10
            )
        )
    ),
    Tr(
        td(
checkbox(-name=>'use',
               -value=>'yes',
               -label=>'Use signature'),
        )
    ),       
    Tr(
        td(           
checkbox(-name=>'save',
               -value=>'yes',
               -label=>'Save signature'),
        )

    ),
        td(submit('button','submit'))
    ),
  end_form(), hr();

if ( param() ) {

# rid ourselves from those nasty params
my $message   = param('message');
my $password  = param('password');
my $subject   = param('subject');
my $signature = param('signature');
my $save      = param('save');
my $use       = param('use');
my $time      = localtime;

if ($password ne $lock) {
print "Wrong password.  Email rejected from server.\n";
}
else {
    if ( $message eq "" || $subject eq "" ) {
        print "Your subject or email content was missing.\n";
        exit;
    }
    else {
    
        if ( $save eq "yes" ) {
        print "<br>";
        print "Saving to database<br>\n";
                $sig{'default'} = $signature;
                $sig{'stored'} = $sig{'default'};
        print "\$sig{'default'}: $sig{'default'}<br><br>\n";
    }
    
        foreach my $key ( keys %emails ) {
            print "Things we have: $key <br>\n";
        }
        print "<br>\n";

        while ( my ( $key, $value ) = each(%emails) ) {
                    # Email Subs, special commands
            $message =~ s/\[name\]/$value/g;    #[name] = user name
            $message =~ s/\[time\]/$time/g;     #[time] = time sent 
            $message =~ s/\[unsub\]/$unsub/g;   #[unsub] = unsubscribe
+ email  

            $editsig = $signature;              # so we can fiddle wit
+h it
            $editsig =~ s/\[name\]/$value/g;    #[name] = user name
            $editsig =~ s/\[time\]/$time/g;     #[time] = time sent 
            $editsig =~ s/\[unsub\]/$unsub/g;   #[unsub] = unsubscribe
+ email              
             
            $subject =~ s/\[name\]/$value/g;    #[name] = user name
        
            open( MAIL, "| $sendmail -t" );
            print MAIL "To: $key\n";
            print MAIL "From: $adminmail\n";
            print MAIL "Subject: $subject\n\n";
            print MAIL "$message\n";
             if ( $use eq "yes" && $signature ne "" ) {          
                print MAIL "$editsig\n";
            }
            print MAIL ".\n";
            close(MAIL);

            print "Email was sent to: $key !<br>";
        }
    }

}
}

untie %emails;
untie %sig;
[download]