
I know that there is an OpenARC library, but I wouldn't know where to start with implementing it.
Of course, I appreciate that ARC is technically still in draft form, but it has now been implemented by Google, so others will follow suit soon.
I have come to have an interest in this, after fighting for many hours to work out why e-mails weren't being received by the recipient when my server was the intermediary (As is common, and recognised, for mailing lists). In this instance I didn't want to completely re-write the message (new from / dkim / reply to etc), but some (possible) fault in hMailServer's scripting oMessage.addHeader / oMessage.Save was removing a CRLF from the boundary lines and changing it to a space in the body. This was breaking the DKIM bodyhash, therefore the DMARC which was set to reject

Increasingly, the large MX (Google, Yahoo, Hotmail) are implementing strict DKIM, SPF and DMARC policies. Without SRS (Sender Rewriting Scheme) and ARC, we will soon be completely unable to forward messages. We will only be able to send messages out from our servers and receive them in. Obviously, real life is a little more varied, and ARC is the acknowledgment of that. I think that ARC will therefore be needed if we are to continue to be able to forward messages...
Would appreciate others' more enlightened thoughts on this!