fix: send email with local name via custom client (#607)

* fix: send email with local name via custom client

* remove unneeded (duplicated) checks

* add `local-name` to a config file

* remove unneeded `return`

* change logs

* refactor: using smtp.Dial()

* add comments for the new fuction

* update: change a field name

actions/email.go

@@ -1,6 +1,7 @@
 package actions
 
 import (
+	"crypto/tls"
 	"errors"
 	"fmt"
 	"log"
@@ -19,15 +20,16 @@ var (
 )
 
 type EmailAction struct {
-	Name       string
-	User       string
-	Password   string
-	Host       string
-	Port       int
-	Sender     string
-	Recipients []string
-	UseMX      bool
-	sendFunc   func(addr string, a smtp.Auth, from string, to []string, msg []byte) error
+	Name           string
+	User           string
+	Password       string
+	Host           string
+	Port           int
+	Sender         string
+	Recipients     []string
+	ClientHostName string
+	UseMX          bool
+	sendFunc       func(addr string, a smtp.Auth, from string, to []string, msg []byte) error
 }
 
 func (email *EmailAction) GetName() string {
@@ -39,8 +41,13 @@ func (email *EmailAction) Init() error {
 	if email.Sender == "" {
 		email.Sender = email.User
 	}
+	if email.ClientHostName != "" {
+		log.Printf("Action %q uses a custom client name %q instead of `localhost`", email.Name, email.ClientHostName)
+		email.sendFunc = email.sendEmailWithCustomClient
+	} else {
+		email.sendFunc = smtp.SendMail
+	}
 
-	email.sendFunc = smtp.SendMail
 	return nil
 }
 
@@ -89,6 +96,56 @@ func (email *EmailAction) Send(content map[string]string) error {
 	return nil
 }
 
+// sendEmailWithCustomClient replaces smtp.SendMail() in cases
+// where it is necessary to establish a custom client host name instead of "localhost",
+// while keeping the remaining behavior unchanged.
+func (email EmailAction) sendEmailWithCustomClient(addr string, a smtp.Auth, from string, to []string, msg []byte) error {
+	log.Printf("Sending an email via Custom client for action %q", email.Name)
+
+	c, err := smtp.Dial(addr)
+	if err != nil {
+		return err
+	}
+	defer c.Close()
+
+	if err := c.Hello(email.ClientHostName); err != nil {
+		return err
+	}
+
+	if ok, _ := c.Extension("STARTTLS"); ok {
+		config := &tls.Config{ServerName: email.Host}
+		if err = c.StartTLS(config); err != nil {
+			return err
+		}
+	}
+	if a != nil {
+		if err = c.Auth(a); err != nil {
+			return err
+		}
+	}
+	if err = c.Mail(from); err != nil {
+		return err
+	}
+	for _, addr := range to {
+		if err = c.Rcpt(addr); err != nil {
+			return err
+		}
+	}
+	w, err := c.Data()
+	if err != nil {
+		return err
+	}
+	_, err = w.Write(msg)
+	if err != nil {
+		return err
+	}
+	err = w.Close()
+	if err != nil {
+		return err
+	}
+	return c.Quit()
+}
+
 func (email EmailAction) sendViaMxServers(port string, msg string, recipients []string) {
 	for _, rcpt := range recipients {
 		at := strings.LastIndex(rcpt, "@")

cfg.yaml

@@ -96,6 +96,7 @@ actions:
   host:      # Mandatory: SMTP host name (e.g. smtp.gmail.com)
   port:      # Mandatory: SMTP server port (e.g. 587)
   sender:    # Mandatory: The email address to use as a sender
+  client-host-name: # Optional: setting the local client name instead of `localhost`
   recipients: ["", ""]  # Mandatory: comma separated list of recipients
 
 - name: my-email-smtp-server

router/builders.go

@@ -64,14 +64,15 @@ func buildSlackAction(sourceSettings *ActionSettings, aqua string) *actions.Slac
 
 func buildEmailAction(sourceSettings *ActionSettings) *actions.EmailAction {
 	return &actions.EmailAction{
-		Name:       sourceSettings.Name,
-		User:       sourceSettings.User,
-		Password:   sourceSettings.Password,
-		Host:       sourceSettings.Host,
-		Port:       sourceSettings.Port,
-		Sender:     sourceSettings.Sender,
-		Recipients: sourceSettings.Recipients,
-		UseMX:      sourceSettings.UseMX,
+		Name:           sourceSettings.Name,
+		User:           sourceSettings.User,
+		Password:       sourceSettings.Password,
+		Host:           sourceSettings.Host,
+		Port:           sourceSettings.Port,
+		Sender:         sourceSettings.Sender,
+		Recipients:     sourceSettings.Recipients,
+		ClientHostName: sourceSettings.ClientHostName,
+		UseMX:          sourceSettings.UseMX,
 	}
 }
 func buildNexusIqAction(sourceSettings *ActionSettings) *actions.NexusIqAction {

router/integrations.go

@@ -25,6 +25,7 @@ type ActionSettings struct {
 	Recipients            []string                     `json:"recipients,omitempty"`
 	Sender                string                       `json:"sender,omitempty"`
 	Token                 string                       `json:"token,omitempty"`
+	ClientHostName        string                       `json:"client-host-name,omitempty"`
 	UseMX                 bool                         `json:"use-mx,omitempty"`
 	InstanceName          string                       `json:"instance,omitempty"`
 	SizeLimit             int                          `json:"size-limit,omitempty"`