update

ts/mail/delivery/smtpclient/command-handler.ts

@@ -54,7 +54,10 @@ export class CommandHandler extends EventEmitter {
    * Send MAIL FROM command
    */
   public async sendMailFrom(connection: ISmtpConnection, fromAddress: string): Promise<ISmtpResponse> {
-    const command = `${SMTP_COMMANDS.MAIL_FROM}:<${fromAddress}>`;
+    // Handle empty return path for bounce messages
+    const command = fromAddress === '' 
+      ? `${SMTP_COMMANDS.MAIL_FROM}:<>` 
+      : `${SMTP_COMMANDS.MAIL_FROM}:<${fromAddress}>`;
     return this.sendCommand(connection, command);
   }
   
@@ -77,15 +80,19 @@ export class CommandHandler extends EventEmitter {
    * Send email data content
    */
   public async sendDataContent(connection: ISmtpConnection, emailData: string): Promise<ISmtpResponse> {
-    // Ensure email data ends with CRLF.CRLF
-    let data = emailData;
+    // Normalize line endings to CRLF
+    let data = emailData.replace(/\r\n/g, '\n').replace(/\r/g, '\n').replace(/\n/g, '\r\n');
+    
+    // Ensure email data ends with CRLF
     if (!data.endsWith(LINE_ENDINGS.CRLF)) {
       data += LINE_ENDINGS.CRLF;
     }
-    data += '.' + LINE_ENDINGS.CRLF;
     
     // Perform dot stuffing (escape lines starting with a dot)
-    data = data.replace(/\n\./g, '\n..');
+    data = data.replace(/\r\n\./g, '\r\n..');
+    
+    // Add termination sequence
+    data += '.' + LINE_ENDINGS.CRLF;
     
     return this.sendRawData(connection, data);
   }
@@ -306,7 +313,7 @@ export class CommandHandler extends EventEmitter {
       const response = parseSmtpResponse(this.responseBuffer);
       this.responseBuffer = '';
       
-      if (isSuccessCode(response.code) || response.code >= 400) {
+      if (isSuccessCode(response.code) || (response.code >= 300 && response.code < 400) || response.code >= 400) {
         this.pendingCommand.resolve(response);
       } else {
         this.pendingCommand.reject(new Error(`Command failed: ${response.message}`));

ts/mail/delivery/smtpclient/smtp-client.ts

@@ -57,20 +57,27 @@ export class SmtpClient extends EventEmitter {
    */
   public async sendMail(email: Email): Promise<ISmtpSendResult> {
     const startTime = Date.now();
-    const fromAddress = email.from;
-    const recipients = Array.isArray(email.to) ? email.to : [email.to];
+    
+    // Extract clean email addresses without display names for SMTP operations
+    const fromAddress = email.getFromAddress();
+    const recipients = email.getToAddresses();
+    const ccRecipients = email.getCcAddresses();
+    const bccRecipients = email.getBccAddresses();
+    
+    // Combine all recipients for SMTP operations
+    const allRecipients = [...recipients, ...ccRecipients, ...bccRecipients];
     
     // Validate email addresses
     if (!validateSender(fromAddress)) {
       throw new Error(`Invalid sender address: ${fromAddress}`);
     }
     
-    const recipientErrors = validateRecipients(recipients);
+    const recipientErrors = validateRecipients(allRecipients);
     if (recipientErrors.length > 0) {
       throw new Error(`Invalid recipients: ${recipientErrors.join(', ')}`);
     }
     
-    logEmailSend('start', recipients, this.options);
+    logEmailSend('start', allRecipients, this.options);
     
     let connection: ISmtpConnection | null = null;
     const result: ISmtpSendResult = {
@@ -79,7 +86,7 @@ export class SmtpClient extends EventEmitter {
       rejectedRecipients: [],
       envelope: {
         from: fromAddress,
-        to: recipients
+        to: allRecipients
       }
     };
     
@@ -114,8 +121,8 @@ export class SmtpClient extends EventEmitter {
         throw new Error(`MAIL FROM failed: ${mailFromResponse.message}`);
       }
       
-      // Send RCPT TO for each recipient
-      for (const recipient of recipients) {
+      // Send RCPT TO for each recipient (includes TO, CC, and BCC)
+      for (const recipient of allRecipients) {
         try {
           const rcptResponse = await this.commandHandler.sendRcptTo(connection, recipient);
           if (rcptResponse.code >= 400) {

ts/mail/delivery/smtpclient/utils/validation.ts

@@ -8,12 +8,28 @@ import type { ISmtpClientOptions, ISmtpAuthOptions } from '../interfaces.js';
 
 /**
  * Validate email address format
+ * Supports RFC-compliant addresses including empty return paths for bounces
  */
 export function validateEmailAddress(email: string): boolean {
-  if (!email || typeof email !== 'string') {
+  if (typeof email !== 'string') {
     return false;
   }
-  return REGEX_PATTERNS.EMAIL_ADDRESS.test(email.trim());
+  
+  const trimmed = email.trim();
+  
+  // Handle empty return path for bounce messages (RFC 5321)
+  if (trimmed === '' || trimmed === '<>') {
+    return true;
+  }
+  
+  // Handle display name formats
+  const angleMatch = trimmed.match(/<([^>]+)>/);
+  if (angleMatch) {
+    return REGEX_PATTERNS.EMAIL_ADDRESS.test(angleMatch[1]);
+  }
+  
+  // Regular email validation
+  return REGEX_PATTERNS.EMAIL_ADDRESS.test(trimmed);
 }
 
 /**