If you want the line endings to be preserved, you can just iterate over the lines: 
for (@{$msg->body}){
    s/\bblah\b/something/g;
    print;
}

[download]

It does nearly the same thing as your original loop, but it has a slightly different notion of where a word ends.

If you really want whitespace delimited words you can change the regular expression to read

s/(?<=^| )blah(?= |$)/something/g;

In reply to Re: A regex question by moritz
in thread A regex question by vxp

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