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\part{TESTING}
openarc.org provides infrastructure you may use to get familar with ARC.

\section{1. Autoresponder}
Send a message to echo@openarc.org. You'll receive a response seconds later. This response contain the message as received by the service. This allowes you to inspect how OpenARC validate your sent message.

\section{2. Forwarder}
Send a message to forward@openarc.org. You'll receive your message \textsl{forwarded} back to you seconds later. It's not a new one. Existing DKIM signatures are expected to be still intact after forwarding.

But you may force message modification to invalidate your existing DKIM signature: Choose the text "modify" as Subject and it will be prepended with "[MODIFIED]: " on forwarding. Your DKIM signature will be no longer valid. We assume you sign the RFC5322.Subject header as advised by RFC 6376 - DKIM Signatures\footnote{https://tools.ietf.org/html/rfc6376\#section-5.4}

You may also choose the text "add" as Subject and it will add a second Subject header into your message. That way you could see DKIM signatures stay valid unless you use oversigning. Background\footnote{http://noxxi.de/research/breaking-dkim-on-purpose-and-by-chance.html} and DKIM SPEC\footnote{https://tools.ietf.org/html/rfc6376\#section-8.15}

\section{3. Mailing-List}
Subscribe\footnote{mailto:openarc-testing+subscribe@openarc.org} to the mailing list first. Then you may send messages to openarc-testing@openarc.org. As usual your message is resend to all subscriber. There is no public list archive as that donsn't make sense.

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