Füge Message-Id zur Mail hinzu

repositories/request.go

@@ -7,6 +7,7 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"html/template"
 	"log"
 	"math/big"
 	"net/smtp"
@@ -128,9 +129,10 @@ func (r *RequestRepo) newSecret() (string, error) {
 func (r *RequestRepo) sendConfirmationMail(request models.Request) error {
 	var message bytes.Buffer
 	var data = struct {
-		Config  config.Config
-		Request models.Request
-	}{r.config, request}
+		Config    config.Config
+		Request   models.Request
+		MessageId template.HTML
+	}{r.config, request, template.HTML("<" + randomString(15) + "@" + r.config.Server.Domain + ">")}
 	err := templating.WriteTemplate(&message, "confirmationMail", data)
 	if err != nil {
 		err = fmt.Errorf("Error parsing confirmation Mail: %w", err)

templating/templates/confirmationMail

@@ -1,6 +1,7 @@
 From: {{.Config.Mailer.FromName}}
 To: {{.Request.OfficeHour.Tutor.Email}}
 Subject: Sprechstunde {{if eq .Request.Action 1}}anlegen{{end}}{{if eq .Request.Action 2}}löschen{{end}}
+Message-Id: {{.MessageId}}
 
 Hallo {{.Request.OfficeHour.Tutor.Name}},