It depends on what lies inside the $k elements of @$data, but either way, you may want to move your foreach loop to something roughly like:

print<<_WML_;
        <?xml version='1.0'?>
        <!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.1//EN"
        "http://www.wapforum.org/DTD/wml_1.1.xml">
        <wml>
        <card title="smsbook" id="smsbook">
_WML_

my ($data,$rows) = &get_sms($dbh,$userid);
my $k;
foreach $k (@$data){
      print "<p>", @$k, "</p>\n";
}

print "
        </card>
       </wml>
";
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