feat: Allow plaintext e-mails for SMTP

Adds `--plaintext` flag which allows sending
e-mails in plaintext with SMTP method.

Also adds counterpart POP_PLAINTEXT.

Not implemented for the Resend method.

Author: jficz

email.go

@@ -42,7 +42,7 @@ func (m Model) sendEmailCmd() tea.Cmd {
 		bcc := strings.Split(m.Bcc.Value(), ToSeparator)
 		switch m.DeliveryMethod {
 		case SMTP:
-			err = sendSMTPEmail(to, cc, bcc, m.From.Value(), m.Subject.Value(), m.Body.Value(), attachments)
+			err = sendSMTPEmail(to, cc, bcc, m.From.Value(), m.Subject.Value(), m.Body.Value(), plaintext, attachments)
 		case Resend:
 			err = sendResendEmail(to, cc, bcc, m.From.Value(), m.Subject.Value(), m.Body.Value(), attachments)
 		default:
@@ -63,7 +63,7 @@ const gmailSuffix = "@gmail.com"
 const gmailSMTPHost = "smtp.gmail.com"
 const gmailSMTPPort = 587
 
-func sendSMTPEmail(to, cc, bcc []string, from, subject, body string, attachments []string) error {
+func sendSMTPEmail(to, cc, bcc []string, from, subject, body string, plaintext bool, attachments []string) error {
 	server := mail.NewSMTPClient()
 
 	var err error
@@ -115,7 +115,7 @@ func sendSMTPEmail(to, cc, bcc []string, from, subject, body string, attachments
 	html := bytes.NewBufferString("")
 	convertErr := goldmark.Convert([]byte(body), html)
 
-	if convertErr != nil {
+	if (plaintext) || (convertErr != nil) {
 		email.SetBody(mail.TextPlain, body)
 	} else {
 		email.SetBody(mail.TextHTML, html.String())

main.go

@@ -20,6 +20,10 @@ import (
 // email body.
 const PopUnsafeHTML = "POP_UNSAFE_HTML"
 
+// PopPlaintext control whether the message should be sent in plaintext.
+// Boolean, default `false`
+const PopPlaintext = "POP_PLAINTEXT"
+
 // ResendAPIKey is the environment variable that enables Resend as a delivery
 // method and uses it to send the email.
 const ResendAPIKey = "RESEND_API_KEY" //nolint:gosec
@@ -56,6 +60,7 @@ var (
 	bcc                    []string
 	subject                string
 	body                   string
+	plaintext              bool
 	attachments            []string
 	preview                bool
 	unsafe                 bool
@@ -119,7 +124,7 @@ var rootCmd = &cobra.Command{
 			var err error
 			switch deliveryMethod {
 			case SMTP:
-				err = sendSMTPEmail(to, cc, bcc, from, subject, body, attachments)
+				err = sendSMTPEmail(to, cc, bcc, from, subject, body, plaintext, attachments)
 			case Resend:
 				err = sendResendEmail(to, cc, bcc, from, subject, body, attachments)
 			default:
@@ -201,6 +206,8 @@ func init() {
 	rootCmd.Flags().StringSliceVarP(&attachments, "attach", "a", []string{}, "Email's attachments")
 	rootCmd.Flags().StringSliceVarP(&to, "to", "t", []string{}, "Recipients")
 	rootCmd.Flags().StringVarP(&body, "body", "b", "", "Email's contents")
+	envPlaintext := os.Getenv(PopPlaintext) == "true"
+	rootCmd.Flags().BoolVar(&plaintext, "plaintext", envPlaintext, "Whether to send email in plaintext")
 	envFrom := os.Getenv(PopFrom)
 	rootCmd.Flags().StringVarP(&from, "from", "f", envFrom, "Email's sender"+commentStyle.Render("($"+PopFrom+")"))
 	rootCmd.Flags().StringVarP(&subject, "subject", "s", "", "Email's subject")