Added Unicode email address validation

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

@@ -70,6 +70,7 @@ import java.security.cert.X509Certificate;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.regex.Pattern;
 
 import javax.mail.internet.AddressException;
 import javax.mail.internet.InternetAddress;
@@ -757,8 +758,11 @@ public class FragmentIdentity extends FragmentBase {
                 //    throw new IllegalArgumentException(context.getString(R.string.title_no_name));
                 if (TextUtils.isEmpty(email) && !should)
                     throw new IllegalArgumentException(context.getString(R.string.title_no_email));
-                if (!Helper.EMAIL_ADDRESS.matcher(email).matches() && !should)
+
+                Pattern pattern = (unicode ? Helper.EMAIL_ADDRESS_UNICODE : Helper.EMAIL_ADDRESS);
+                if (!pattern.matcher(email).matches() && !should)
                     throw new IllegalArgumentException(context.getString(R.string.title_email_invalid, email));
+
                 if (TextUtils.isEmpty(host) && !should)
                     throw new IllegalArgumentException(context.getString(R.string.title_no_host));
                 if (TextUtils.isEmpty(port))

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

@@ -192,8 +192,7 @@ public class Helper {
     private static final String[] ROMAN_10 = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"};
     private static final String[] ROMAN_1 = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"};
 
-    static final Pattern EMAIL_ADDRESS
-            = Pattern.compile(
+    static final Pattern EMAIL_ADDRESS = Pattern.compile(
             "[\\S]{1,256}" +
                     "\\@" +
                     "[a-zA-Z0-9][a-zA-Z0-9\\-]{0,64}" +
@@ -203,6 +202,14 @@ public class Helper {
                     ")+"
     );
 
+    static final Pattern EMAIL_ADDRESS_UNICODE = Pattern.compile(
+            "([\\p{L}\\_\\.\\-\\d]+)" +
+                    "@" +
+                    "([\\p{L}\\-\\.\\d]+)" +
+                    "((\\.(\\p{L}){2,63})+)"
+            // ^([\p{L}\_\.\-\d]+)@([\p{L}\-\.\d]+)((\.(\p{L}){2,63})+)$
+    );
+
     private static final ExecutorService executor = getBackgroundExecutor(1, "helper");
 
     static ExecutorService getBackgroundExecutor(int threads, final String name) {