Your code is littered with parts not relevant to the problem. Please reduce it by removing all parts of your program that do not relate to Mail::DKIM and getting a result from it. Also, I would assume that the result of the DKIM verifier depends on the input message, which you haven't supplied. Note that Mail::DKIM::Verifier seems to want SMTP-style line endings (\r\n), which your raw reading of a file might or might not produce.