9
9
RFC 6008 DKIM signature identification (header.b)
10
10
RFC 6212 Vouch By Reference (VBR)
11
11
RFC 6577 Sender Policy Framework (SPF)
12
13
RFC 7281 Authentication-Results Registration for S/MIME
13
14
RFC 7293, The Require-Recipient-Valid-Since Header Field
14
15
and SMTP Service Extension, header field types
19
18
RFC 7410, A Property Types Registry for the Authentication-Results Header
20
19
Field, added the possibility for new ptypes to be created, but so far none