Forum OpenACS Q&A: problem in executing ns_sendmail

I am trying to execute ns_sendmail command but it displays following errors ;


    could not connect to "localhost:25"
        while executing
    "ns_sockopen $smtp $smtpport"
        (procedure "_ns_sendmail" line 31)
        invoked from within
    "_ns_sendmail $smtp $smtpport $timeout $tolist $bcclist  $from $subject $body $extraheaders"
        (procedure "ns_sendmail" line 58)
        invoked from within
    "ns_sendmail $admin_email  "mailto:pkh_nik@indiatimes.com"; "Request for approval regarding room Reservation" $msg $extraheaders "
        invoked from within
    "if { [string compare $requires_permission_p "Y"] } {

      db_dml assign_room  "insert into reservations values ($room_id,$start_time,$end_time,$user_id,..."
        (file "/webroot/pharshwal/www/reserve/new-2.tcl" line 15)
        invoked from within
    "source [ad_conn file]"
        (procedure "rp_handle_tcl_request" line 2)
        invoked from within
    "rp_handle_tcl_request"
        invoked from within
    "catch $handler error"
        invoked from within
    "rp_abstract_url_server"