Expect SOA mailbox in hostmaster@example.org format instead of hostmaster.example.org (#2037)

Co-authored-by: Yannik Sembritzki <yannik@sembritzki.org>
Co-authored-by: Tom Limoncelli <tlimoncelli@stackoverflow.com>

pkg/soautil/soautil_test.go

@@ -0,0 +1,28 @@
+package soautil
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_RFC5322MailToBind(t *testing.T) {
+	type args struct {
+		rfc5322Mail string
+	}
+	tests := []struct {
+		name        string
+		rfc5322Mail string
+		bindMail    string
+	}{
+		{"0", "hostmaster@example.com", "hostmaster.example.com"},
+		{"1", "admin.dns@example.com", "admin\\.dns.example.com"},
+		{"2", "hostmaster@sub.example.com", "hostmaster.sub.example.com"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := RFC5322MailToBind(tt.rfc5322Mail); !reflect.DeepEqual(got, tt.bindMail) {
+				t.Errorf("RFC5322MailToBind(%v) = %v, want %v", tt.rfc5322Mail, got, tt.bindMail)
+			}
+		})
+	}
+}