I have a script for this that I use all the time. Just put it in a reachable path and make it executable.

#!/usr/bin/perl -l

for (@ARGV) {
  (my $a.="$_.pm") =~s#::#/#g;
  eval {
    require $a;
  };
  print "$_: ",$@?"Not found":$INC{$a};
}
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Then you just call it with:

findmod LWP::Simple Mail::Sendmail
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While I'm on the subject, I also find this script to be really helpful:

#!/usr/bin/perl -l
$_=shift;
($_.=".pm")=~s#::#/#g;
eval { require $_ };
exec("vi",$INC{$_}) unless $@;
print "Module not found"
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And I call it as:

editmod LWP::Simple
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