Add TLS to SMTP config

config.toml.sample

@@ -84,7 +84,7 @@ max_idle = 10
     [smtp.my0]
         enabled = true
         host = "my.smtp.server"
-        port = "25"
+        port = 25
 
         # "cram", "plain", or "login". Empty string for no auth.
         auth_protocol = "cram"
@@ -112,10 +112,14 @@ max_idle = 10
         # The number of times a message should be retried if sending fails.
 	    max_msg_retries = 2
 
+        # Enable STARTTLS.
+        tls_enabled = true
+        tls_skip_verify = false
+
     [smtp.postal]
         enabled = false
         host = "my.smtp.server2"
-        port = "25"
+        port = 25
 
         # cram or plain.
         auth_protocol = "plain"
@@ -143,6 +147,9 @@ max_idle = 10
         # The number of times a message should be retried if sending fails.
 	    max_msg_retries = 2
 
+        # Enable STARTTLS.
+        tls_enabled = true
+        tls_skip_verify = false
 
 [upload]
 # File storage backend. "filesystem" or "s3".

go.mod

@@ -22,4 +22,3 @@ require (
 	gopkg.in/volatiletech/null.v6 v6.0.0-20170828023728-0bef4e07ae1b
 	jaytaylor.com/html2text v0.0.0-20200220170450-61d9dc4d7195
 )
-

internal/messenger/emailer.go

@@ -1,6 +1,7 @@
 package messenger
 
 import (
+	"crypto/tls"
 	"fmt"
 	"math/rand"
 	"net/smtp"
@@ -18,6 +19,8 @@ type Server struct {
 	Password      string `json:"password"`
 	AuthProtocol  string `json:"auth_protocol"`
 	EmailFormat   string `json:"email_format"`
+	TLSEnabled    bool   `json:"tls_enabled"`
+	TLSSkipVerify bool   `json:"tls_skip_verify"`
 
 	// Rest of the options are embedded directly from the smtppool lib.
 	// The JSON tag is for config unmarshal to work.
@@ -35,13 +38,13 @@ type Emailer struct {
 
 // NewEmailer creates and returns an e-mail Messenger backend.
 // It takes multiple SMTP configurations.
-func NewEmailer(srv ...Server) (*Emailer, error) {
+func NewEmailer(servers ...Server) (*Emailer, error) {
 	e := &Emailer{
 		servers: make(map[string]*Server),
 	}
 
-	for _, server := range srv {
-		s := server
+	for _, srv := range servers {
+		s := srv
 		var auth smtp.Auth
 		switch s.AuthProtocol {
 		case "cram":
@@ -56,6 +59,16 @@ func NewEmailer(srv ...Server) (*Emailer, error) {
 		}
 		s.Opt.Auth = auth
 
+		// TLS config.
+		if s.TLSEnabled {
+			s.TLSConfig = &tls.Config{}
+			if s.TLSSkipVerify {
+				s.TLSConfig.InsecureSkipVerify = s.TLSSkipVerify
+			} else {
+				s.TLSConfig.ServerName = s.Host
+			}
+		}
+
 		pool, err := smtppool.New(s.Opt)
 		if err != nil {
 			return nil, err