JH/08 Pipeline CHUNKING command and data together, on kernels that support
MSG_MORE. Only in-clear (not on TLS connections).
+JH/09 Avoid using a temporary file during transport using dkim. Unless a
+ transport-filter is involved we can buffer the headers in memory for
+ creating the signature, and read the spool data file once for the
+ signature and again for transmission.
+
Exim version 4.89
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