Sebb

The optional nonce makes things worse as there are effectively infinite values it can take. At least with boolean options it would be possible to generate all the different hashes.

@sbp In the case of the nonce, does the additional security rely on using a variable nonce, or would a fixed nonce be sufficient? == Not all emails in archives...

I mean that the Permalink should include the list id, as it does at present. For example: aabbcc@<lid>

If an externally provided list-id is included in the hash, then the has will change if the lid changes. Suppose there is an mbox to be imported. If the individual...

"re-importing from gmail mbox sources, that would not work" - why not? It would certainly work with the mod_mbox software, as that relies on an intrinsic part of the message...

In which case maybe dkim should do the same normalisation as GMail to avoid the issue?

Sorry, but I don't think the discussion is yet complete. We need more reviews by other interested parties. And we need more tests using the same emails from multiple sources.

Another header that should be unfolded is Subject:

When a line is folded, the MTA inserts CRLF followed by a single WSP; unfolding should be the reverse. Multiple WSP should be treated as a single WSP *when it...

No, it's not possible to replace msg by msg_metadata, because that will change the output from the existing generators (at least with some input). I was thinking of adding the...