Well you've been warned :-P [WARN] You have set arguments to pass to Mail::Mailer. Better fix your MTA. (Also, Mail::Mailer's error reporting is non existant, so it won't tell you when it doesn't work.)
As for the error itself, it has nothing to do with caff but with the “non existence“ of Mail::Mailer's error reporting. Rather than making caff (MIME::Entity, actually) use another SMTP client, it'd be easier to improve Mail::Mailer. Cheers, -- Guilhem.
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