OpenDKIM now has enough data to make some interesting observations about signatures and MIME.
As far as MIME encodings go (only the "outermost" encoding was counted), there was a pretty common theme: binary failed 4% of the time quoted-printable failed 4% of the time 7bit failed 7.7% of the time base64 failed 7.8% of the time 8bit failed 14% of the time 16bit (?!) never failed (though there was only one attempt) I expected 8bit to fail more for some reason. As far as MIME parts go (again, only the "outermost" MIME type was counted), most of them have about a 90-93% survival rate which is about in line with general signature survival rates. The one that stands out is "multipart/signed" (from RFC1847) which drops to about a 65% survival rate. I don't know much about how this is typically formatted or treated enroute, but it was easily the biggest outlier in the report. Not sure if that should be a surprise to us or not.
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