Added files.

append.go

@@ -0,0 +1,18 @@
+package imap
+
+import (
+	"time"
+)
+
+// AppendOptions contains options for the APPEND command.
+type AppendOptions struct {
+	Flags []Flag
+	Time  time.Time
+}
+
+// AppendData is the data returned by an APPEND command.
+type AppendData struct {
+	// requires UIDPLUS or IMAP4rev2
+	UID         UID
+	UIDValidity uint32
+}