I strongly recommend going through your code, trying to identify logical "chunks", and pulling them into functions. After you have done that, you will wind up with more maintainable code.

As a side benefit it should then be easy to take the body of your code and turn it into a function that takes an IP address as a parameter. Then you can solve your original problem by calling your function 10 times in a loop.

In case you don't know how to write a function in Perl, you just do it very simply like this:

# declare a function
sub my_function_name {
  # Your input parameters will be in the array @_...
  my $first_arg = shift(@_);
  my @remaining args = @_;

  # Then do whatever you want here...
  print "Hello, world\n";

  # And return data
  return "Whatever you want to\n";
}

# And then you call it like this:
my_function_name("First argument", "the", "rest", "of", "them");
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For more on functions, try perldoc perlsub.

UPDATE
BTW rather than manually calling sendmail, I would recommend using Mail::Send.