Fixed IPv6 SMTP EHLO

app/src/main/java/eu/faircode/email/FragmentIdentity.java

@@ -52,6 +52,7 @@ import com.android.colorpicker.ColorPickerSwatch;
 import com.google.android.material.snackbar.Snackbar;
 import com.google.android.material.textfield.TextInputLayout;
 
+import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
@@ -603,11 +604,12 @@ public class FragmentIdentity extends FragmentBase {
                         else
                             props.put("mail.smtps.localhost", host);
                     } else {
-                        Log.i("Check local address=" + ip.getHostAddress());
+                        String haddr = (ip instanceof Inet6Address ? "IPv6:" : "") + ip.getHostAddress();
+                        Log.i("Check local address=" + haddr);
                         if (starttls)
-                            props.put("mail.smtp.localaddress", ip.getHostAddress());
+                            props.put("mail.smtp.localaddress", haddr);
                         else
-                            props.put("mail.smtps.localaddress", ip.getHostAddress());
+                            props.put("mail.smtps.localaddress", haddr);
                     }
 
                     // Create session

app/src/main/java/eu/faircode/email/Helper.java

@@ -76,6 +76,7 @@ import java.io.OutputStream;
 import java.io.UnsupportedEncodingException;
 import java.net.Inet4Address;
 import java.net.InetAddress;
+import java.net.UnknownHostException;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.text.DateFormat;
@@ -735,11 +736,11 @@ public class Helper {
         return filename.substring(index + 1);
     }
 
-    static InetAddress getLocalIp(Context context) {
+    static InetAddress getLocalIp(Context context) throws UnknownHostException {
         ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
 
         if (android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.M)
-            return null;
+            return InetAddress.getLocalHost();
 
         Network active = cm.getActiveNetwork();
         if (active == null)

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -73,6 +73,7 @@ import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.SocketException;
 import java.net.SocketTimeoutException;
@@ -1947,11 +1948,12 @@ public class ServiceSynchronize extends LifecycleService {
             else
                 props.put("mail.smtps.localhost", ident.host);
         } else {
-            EntityLog.log(ServiceSynchronize.this, "Send local address=" + ip.getHostAddress());
+            String haddr = (ip instanceof Inet6Address ? "IPv6:" : "") + ip.getHostAddress();
+            EntityLog.log(ServiceSynchronize.this, "Send local address=" + haddr);
             if (ident.starttls)
-                props.put("mail.smtp.localaddress", ip.getHostAddress());
+                props.put("mail.smtp.localaddress", haddr);
             else
-                props.put("mail.smtps.localaddress", ip.getHostAddress());
+                props.put("mail.smtps.localaddress", haddr);
         }
 
         // Create session