Phillipp, I've been using your header field folding for a few weeks and I really like it. I think that it should be committed, it's big step forward.
One issue to resolve first: the References header field at the end of this message ends with: <16f13de3df80f62de768420a3cc3a2fe.phil...@bureaucracy.de> <14298-1693614066.188834@mIBq.BRD6.6M0V> There's always an extra space in front of the Message-ID that was appended last. Is that a relic of repl? Or, should the folding code collapse multiple white space characters at the beginning of a line? David