This mIRC script will check /whois and X verify on PM, also it will notify you if user is disconnected and if back connected. It closing PM after 3 minutes of inactivity.

;###################
;# Secured PM/DM   #
;# yM]x @ UnderNet #
;###################

;RAWs/Display WHOIS in Query
RAW 311:*: { if ($query($2)) { /echo $query($2) * $2 $+ ! $+ $3 $+ @ $+ $4- | halt } }
RAW 319:*: { if ($query($2)) { /echo $query($2) * Channels: $3- | halt } }
RAW 312:*: { if ($query($2)) { halt } }
RAW 313:*: { if ($query($2)) { /echo $query($2) * $2 is an IRC Operator | halt } }
RAW 330:*: { if ($query($2)) { /echo $query($2) * $2 is logged as $3 | halt } }
RAW 317:*: { if ($query($2)) { /echo $query($2) * Idle: $duration( $+ $3 $+ ) | halt } }

;On query open it's checking the user
on ^*:OPEN:?:*: {
  /whois $nick $nick
  /.msg x verify $nick
}

;When you write to the user it's reset the timer for closing PM.
on *:INPUT:*: {
  if ($active !ischan) && ($active != Status Window) {
    if ($timer($active)) {
      .timer $+ $active off
    }
    .timer $+ $active 1 180 /close -m $active
  }
}

;When he write you it's reset the timer for closing PM (after you saw the message and text the user back).
on ^*:TEXT:*:?: {
 if ($timer($nick)) {
  .timer $+ $nick off
  .timer $+ $nick 1 180 /close -m $nick
 }
}

;It's displaying the X response of verify in the user query.
on *:NOTICE:*:?: {
 if ( $nick == X ) {
   if ( is === $2 ) {
     if ($query($query(0)) isin $1-) { /echo $query($query(0)) [X] $1- }
   }
 }
}

;It's displaying, in the query query, if s/he has signed out (but you need a common channel).
on *:QUIT:{
  if ($query($nick)) { echo 2 -t $query($nick) * $nick has disconnected from IRC. | /notify $nick }
}

;Notify and proceed the checks when user has returned.
on 1:NOTIFY:{ /query -n $nick | /echo 10 -t $query($nick) * $nick has connected on IRC. | /whois $nick $nick | /.msg x verify $nick }

/load -rs securedpdm.mrc