SMTP: Support disabling encryption (ngoduykhanh#297)

Author: AlexanderS

README.md

@@ -68,7 +68,7 @@ Note:
 | `SMTP_USERNAME`             | The SMTP username                                                                                                                                            | N/A                                |
 | `SMTP_PASSWORD`             | The SMTP user password                                                                                                                                       | N/A                                |
 | `SMTP_AUTH_TYPE`            | The SMTP authentication type. Possible values: `PLAIN`, `LOGIN`, `NONE`                                                                                      | `NONE`                             |
-| `SMTP_ENCRYPTION`           | the encryption method. Possible values: `SSL`, `SSLTLS`, `TLS`, `STARTTLS`                                                                                   | `STARTTLS`                         |
+| `SMTP_ENCRYPTION`           | the encryption method. Possible values: `NONE`, `SSL`, `SSLTLS`, `TLS`, `STARTTLS`                                                                           | `STARTTLS`                         |
 
 ### Defaults for server configuration
 

emailer/smtp.go

@@ -33,6 +33,8 @@ func authType(authType string) mail.AuthType {
 
 func encryptionType(encryptionType string) mail.Encryption {
 	switch strings.ToUpper(encryptionType) {
+	case "NONE":
+		return mail.EncryptionNone
 	case "SSL":
 		return mail.EncryptionSSL
 	case "SSLTLS":

main.go

@@ -61,7 +61,7 @@ func init() {
 	flag.StringVar(&flagSmtpUsername, "smtp-username", util.LookupEnvOrString("SMTP_USERNAME", flagSmtpUsername), "SMTP Username")
 	flag.StringVar(&flagSmtpPassword, "smtp-password", util.LookupEnvOrString("SMTP_PASSWORD", flagSmtpPassword), "SMTP Password")
 	flag.BoolVar(&flagSmtpNoTLSCheck, "smtp-no-tls-check", util.LookupEnvOrBool("SMTP_NO_TLS_CHECK", flagSmtpNoTLSCheck), "Disable TLS verification for SMTP. This is potentially dangerous.")
-	flag.StringVar(&flagSmtpEncryption, "smtp-encryption", util.LookupEnvOrString("SMTP_ENCRYPTION", flagSmtpEncryption), "SMTP Encryption : SSL, SSLTLS, TLS or STARTTLS (by default)")
+	flag.StringVar(&flagSmtpEncryption, "smtp-encryption", util.LookupEnvOrString("SMTP_ENCRYPTION", flagSmtpEncryption), "SMTP Encryption : NONE, SSL, SSLTLS, TLS or STARTTLS (by default)")
 	flag.StringVar(&flagSmtpAuthType, "smtp-auth-type", util.LookupEnvOrString("SMTP_AUTH_TYPE", flagSmtpAuthType), "SMTP Auth Type : PLAIN, LOGIN or NONE.")
 	flag.StringVar(&flagSendgridApiKey, "sendgrid-api-key", util.LookupEnvOrString("SENDGRID_API_KEY", flagSendgridApiKey), "Your sendgrid api key.")
 	flag.StringVar(&flagEmailFrom, "email-from", util.LookupEnvOrString("EMAIL_FROM_ADDRESS", flagEmailFrom), "'From' email address.")