feat(mail): Prefix SMTP environment variables with APPENGINE_

Prefixed all SMTP-related environment variables (e.g., , ) with  to improve namespacing and prevent potential conflicts.

The implementation in  and the corresponding mocks in  have been updated to use the new variable names.

Author: abhishekr700

api/src/main/java/com/google/appengine/api/mail/MailServiceImpl.java

@@ -81,22 +81,22 @@ public void send(Message message)
 
   private void sendSmtp(Message message, boolean toAdmin)
       throws IllegalArgumentException, IOException {
-    String smtpHost = envProvider.getenv("SMTP_HOST");
+    String smtpHost = envProvider.getenv("APPENGINE_SMTP_HOST");
     if (smtpHost == null || smtpHost.isEmpty()) {
       throw new IllegalArgumentException("SMTP_HOST environment variable is not set.");
     }
     Properties props = new Properties();
     props.put("mail.smtp.host", smtpHost);
-    props.put("mail.smtp.port", envProvider.getenv("SMTP_PORT"));
+    props.put("mail.smtp.port", envProvider.getenv("APPENGINE_SMTP_PORT"));
     props.put("mail.smtp.auth", "true");
-    if (Boolean.parseBoolean(envProvider.getenv("SMTP_USE_TLS"))) {
+    if (Boolean.parseBoolean(envProvider.getenv("APPENGINE_SMTP_USE_TLS"))) {
       props.put("mail.smtp.starttls.enable", "true");
     }
 
     Session session = Session.getInstance(props, new javax.mail.Authenticator() {
       protected javax.mail.PasswordAuthentication getPasswordAuthentication() {
         return new javax.mail.PasswordAuthentication(
-            envProvider.getenv("SMTP_USER"), envProvider.getenv("SMTP_PASSWORD"));
+            envProvider.getenv("APPENGINE_SMTP_USER"), envProvider.getenv("APPENGINE_SMTP_PASSWORD"));
       }
     });
 
@@ -109,7 +109,7 @@ protected javax.mail.PasswordAuthentication getPasswordAuthentication() {
       List<InternetAddress> bccRecipients = new ArrayList<>();
 
       if (toAdmin) {
-        String adminRecipients = envProvider.getenv("ADMIN_EMAIL_RECIPIENTS");
+        String adminRecipients = envProvider.getenv("APPENGINE_ADMIN_EMAIL_RECIPIENTS");
         if (adminRecipients == null || adminRecipients.isEmpty()) {
           throw new IllegalArgumentException("Admin recipients not configured.");
         }
@@ -251,7 +251,7 @@ private List<InternetAddress> toInternetAddressList(Collection<String> addresses
    */
   private void doSend(Message message, boolean toAdmin)
       throws IllegalArgumentException, IOException {
-    if ("true".equals(envProvider.getenv("USE_SMTP_MAIL_SERVICE"))) {
+    if ("true".equals(envProvider.getenv("APPENGINE_USE_SMTP_MAIL_SERVICE"))) {
       sendSmtp(message, toAdmin);
       return;
     }

api/src/test/java/com/google/appengine/api/mail/MailServiceImplTest.java

@@ -36,20 +36,20 @@ public class MailServiceImplTest {
 
   @Mock private Transport transport;
   @Mock private Session session;
-  @Mock private SystemEnvironmentProvider envProvider;
+  @Mock private EnvironmentProvider envProvider;
 
   private MailServiceImpl mailService;
 
   @Before
   public void setUp() {
     mailService = new MailServiceImpl(envProvider);
     // Mock environment variables
-    when(envProvider.getenv("USE_SMTP_MAIL_SERVICE")).thenReturn("true");
-    when(envProvider.getenv("SMTP_HOST")).thenReturn("smtp.example.com");
-    when(envProvider.getenv("SMTP_PORT")).thenReturn("587");
-    when(envProvider.getenv("SMTP_USER")).thenReturn("user");
-    when(envProvider.getenv("SMTP_PASSWORD")).thenReturn("password");
-    when(envProvider.getenv("SMTP_USE_TLS")).thenReturn("true");
+    when(envProvider.getenv("APPENGINE_USE_SMTP_MAIL_SERVICE")).thenReturn("true");
+    when(envProvider.getenv("APPENGINE_SMTP_HOST")).thenReturn("smtp.example.com");
+    when(envProvider.getenv("APPENGINE_SMTP_PORT")).thenReturn("587");
+    when(envProvider.getenv("APPENGINE_SMTP_USER")).thenReturn("user");
+    when(envProvider.getenv("APPENGINE_SMTP_PASSWORD")).thenReturn("password");
+    when(envProvider.getenv("APPENGINE_SMTP_USE_TLS")).thenReturn("true");
   }
 
   @Test
@@ -507,7 +507,7 @@ public void testSendSmtp_customHeaders() throws IOException, MessagingException
   @Test
   public void testSendSmtp_disabledTls() throws IOException, MessagingException {
     // Setup
-    when(envProvider.getenv("SMTP_USE_TLS")).thenReturn("false");
+    when(envProvider.getenv("APPENGINE_SMTP_USE_TLS")).thenReturn("false");
     try (MockedStatic<Session> mockedSession = mockStatic(Session.class)) {
       ArgumentCaptor<Properties> propsCaptor = ArgumentCaptor.forClass(Properties.class);
       mockedSession
@@ -534,7 +534,7 @@ public void testSendSmtp_disabledTls() throws IOException, MessagingException {
   @Test
   public void testSendSmtp_adminEmail() throws IOException, MessagingException {
     // Setup
-    when(envProvider.getenv("ADMIN_EMAIL_RECIPIENTS"))
+    when(envProvider.getenv("APPENGINE_ADMIN_EMAIL_RECIPIENTS"))
         .thenReturn("admin1@example.com,admin2@example.com");
     try (MockedStatic<Session> mockedSession = mockStatic(Session.class)) {
       mockedSession.when(() -> Session.getInstance(any(Properties.class), any())).thenReturn(session);
@@ -570,7 +570,7 @@ public void testSendSmtp_adminEmail() throws IOException, MessagingException {
   @Test(expected = IllegalArgumentException.class)
   public void testSendSmtp_adminEmailNoRecipients() throws IOException, MessagingException {
     // Setup
-    when(envProvider.getenv("ADMIN_EMAIL_RECIPIENTS")).thenReturn(null);
+    when(envProvider.getenv("APPENGINE_ADMIN_EMAIL_RECIPIENTS")).thenReturn(null);
 
     // Create a simple message
     MailService.Message message = new MailService.Message();
@@ -627,7 +627,7 @@ public void testSendSmtp_connectionFailure() throws IOException, MessagingExcept
   @Test(expected = IllegalArgumentException.class)
   public void testSendSmtp_missingSmtpHost() throws IOException, MessagingException {
     // Setup
-    when(envProvider.getenv("SMTP_HOST")).thenReturn(null);
+    when(envProvider.getenv("APPENGINE_SMTP_HOST")).thenReturn(null);
 
     // Create a simple message
     MailService.Message message = new MailService.Message();