If you ever receive the error 451:
Warning: mail(): SMTP server response: 451 See http://pobox.com/~djb/docs/smtplf.html. in…
This is a server error and the command has been aborted due to a server error. It’s not your fault. Your form or shopping cart is sending mail with “bare LFs” which Qmail doesn’t support. While Qmail is following the official mail standards, most mailers ignore this problem and send the mail anyway. But, if you’re hosted here then there is not much you can do!
How to solve the problem when sending data from a form or shopping cart:
Go into the mailer code and replace all the “n” with “rn” – Your code will now be working 
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