One solution is to change the delimiter in your text file to something that will not be present in the input field.

For example you could use a double linefeed to seperate records then single line feeds would not end your record. This has the obvious problem of what if the user enters a blank line. You could trim any double linefeeds out of course and this method retains the format that the user put the data into the form as a side effect.

The problem with the current code which would be noted under use warnings; is that you are making up a new copy of address 3 times in the code.

my $address=$query->param('address');
$address =~ s/\n/<br>/g;
$address =~ s/\r//g;
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See if that makes it better. warnings would say some thing similar to: my declaration masks variable in same scope.