lib/email: set the Date and Message-ID on Message Pack

Calling Pack now set the Date header if its not exist, using the local
time;  and the message-id header if its not exist using the following
format:

	<epoch>.<random-8-chars>@<local-hostname>

The random-8-chars is Seed-ed from Epoch(), so does the boundary.

1 files changed, 17 insertions, 9 deletions

diff --git a/lib/smtp/mail_tx_example_test.go b/lib/smtp/mail_tx_example_test.go
index 33ebbee3..a4b6df0a 100644
--- a/lib/smtp/mail_tx_example_test.go
+++ b/lib/smtp/mail_tx_example_test.go
@@ -8,7 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"log"
-	"math/rand"
+	"os"
 	"regexp"
 	"time"
 
@@ -39,12 +39,12 @@ func ExampleNewMailTx() {
 		mboxes     []*email.Mailbox
 		msg        *email.Message
 		mailtx     *MailTx
+		reDate     *regexp.Regexp
+		hostname   string
 		data       []byte
 		err        error
 	)
 
-	rand.Seed(42)
-
 	mboxes, err = email.ParseMailboxes(toAddresses)
 	if err != nil {
 		log.Fatal(err)
@@ -75,15 +75,22 @@ func ExampleNewMailTx() {
 	fmt.Printf("Tx Recipients: %s\n", mailtx.Recipients)
 
 	// In order to make the example Output works, we need to replace all
-	// CRLF with LF and "date:" with the system timezone.
+	// CRLF with LF, "date:" with the system timezone, and message-id
+	// hostname with fixed "hostname".
 	data = bytes.ReplaceAll(mailtx.Data, []byte("\r\n"), []byte("\n"))
 
 	//fmt.Printf("timeNowUtc: %s\n", timeNowUtc)
 	//fmt.Printf("dateNowUtc: %s\n", dateNowUtc)
 
-	reDate := regexp.MustCompile(`^date: Wed(.*) \+....`)
+	reDate = regexp.MustCompile(`^date: Wed(.*) \+....`)
 	data = reDate.ReplaceAll(data, []byte(`date: `+dateNowUtc))
 
+	hostname, err = os.Hostname()
+	if err != nil {
+		log.Fatal(err)
+	}
+	data = bytes.Replace(data, []byte(hostname), []byte("hostname"), 1)
+
 	fmt.Printf("Tx Data:\n%s", data)
 	//Output:
 	//Tx From: Postmaster <postmaster@mail.example.com>
@@ -94,19 +101,20 @@ func ExampleNewMailTx() {
 	//to: John <john@example.com>, Jane <jane@example.com>
 	//subject: Example subject
 	//mime-version: 1.0
-	//content-type: multipart/alternative; boundary=1b4df158039f7cce49f0a64b0ea7b7dd
+	//content-type: multipart/alternative; boundary=QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf
+	//message-id: <1645600000.QoqDPQfz@hostname>
 	//
-	//--1b4df158039f7cce49f0a64b0ea7b7dd
+	//--QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf
 	//mime-version: 1.0
 	//content-type: text/plain; charset="utf-8"
 	//content-transfer-encoding: quoted-printable
 	//
 	//Email body as plain text
-	//--1b4df158039f7cce49f0a64b0ea7b7dd
+	//--QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf
 	//mime-version: 1.0
 	//content-type: text/html; charset="utf-8"
 	//content-transfer-encoding: quoted-printable
 	//
 	//Email body as <b>HTML</b>
-	//--1b4df158039f7cce49f0a64b0ea7b7dd--
+	//--QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf--
 }