+client 127.0.0.1 PORT_D
+??? 220
+HELO xxx
+??? 250
+MAIL FROM:<CALLER@bloggs.com>
+??? 250
+RCPT TO:<a@test.ex>
+??? 250
+DATA
+??? 354
+DKIM-Signature: v=1; a=rsa-sha512; q=dns/txt; c=relaxed/relaxed; d=test.ex;
+ s=sel; h=From:From; bh=6B2m0DINYQYGHTvmDYQAfAm/wCDFh+Oj57jE2G4jz4nAeJfmjTB6tz
+ me+A5nT6AQ4J3N47vffXLG1exv8bzFZw==; b=YFIC4khvqvXRd8I3r3YTdQqG/SbtDIAYTYVkIo3
+ W7Qe+42eI+w1koPY+ocPtZeRBWWjGVbnZNtof7s5x0sRc6fSDZJAQu6RjnP2xEJWsivowXBMuu8id
+ PtqcDhP/3Q/0W85VMalfSC7eCgpnNxfn73ZjPuBZFCc1wMVh5nUmUvo=;