Initialize module and dependencies

vendor/github.com/emersion/go-message/mail/mail.go

@@ -0,0 +1,9 @@
+// Package mail implements reading and writing mail messages.
+//
+// This package assumes that a mail message contains one or more text parts and
+// zero or more attachment parts. Each text part represents a different version
+// of the message content (e.g. a different type, a different language and so
+// on).
+//
+// RFC 5322 defines the Internet Message Format.
+package mail