in fact some of them were inherited from earlier versions.
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-accept_8bitmime boolean false main 1.60
+accept_8bitmime boolean true main 1.60 changed to true in 4.78
acl_not_smtp string* unset main 4.11
acl_not_smtp_mime string* unset main 4.51 with content scan
acl_smtp_auth string* unset main 4.00
once_file_size integer 0 autoreply 3.20
once_repeat time 0s autoreply 2.95
one_time boolean false redirect 4.00
-openssl_options string "+dont_insert_empty_fragments" main 4.73
+openssl_options string unset main 4.73 default to unset in 4.78
optional boolean false iplookup 4.00
oracle_servers string unset main 4.00
owners string list unset redirect 4.00
tls_remember_emstp boolean false main 4.21
tls_require_ciphers string* unset smtp 4.00 replaces tls_verify_ciphers
string* unset main 4.33
+tls_sni string* unset main 4.78
tls_tempfail_tryclear boolean true smtp 4.05
tls_try_verify_hosts host list unset main 4.00
tls_verify_certificates string* unset main 3.20