diff --git a/is_prime b/01_primes/is_prime
similarity index 100%
rename from is_prime
rename to 01_primes/is_prime
diff --git a/readme.md b/01_primes/readme.md
similarity index 100%
rename from readme.md
rename to 01_primes/readme.md
diff --git a/02_MailClient/MailClient.iml b/02_MailClient/MailClient.iml
new file mode 100644
index 0000000..c90834f
--- /dev/null
+++ b/02_MailClient/MailClient.iml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/02_MailClient/src/Main.java b/02_MailClient/src/Main.java
new file mode 100644
index 0000000..f1f2792
--- /dev/null
+++ b/02_MailClient/src/Main.java
@@ -0,0 +1,6 @@
+public class Main {
+    public static void main(String[] args) {
+
+        System.out.println("Hello world!");
+    }
+}
\ No newline at end of file
diff --git a/02_MailClient/src/net/hypki/mailclient/db/Db.java b/02_MailClient/src/net/hypki/mailclient/db/Db.java
new file mode 100644
index 0000000..68402c4
--- /dev/null
+++ b/02_MailClient/src/net/hypki/mailclient/db/Db.java
@@ -0,0 +1,8 @@
+package net.hypki.mailclient.db;
+
+import java.io.IOException;
+
+public interface Db {
+    public void save(String key, Object value) throws IOException;
+    public Object get(String key);
+}
diff --git a/02_MailClient/src/net/hypki/mailclient/db/sql/MySQLDB.java b/02_MailClient/src/net/hypki/mailclient/db/sql/MySQLDB.java
new file mode 100644
index 0000000..88daa0b
--- /dev/null
+++ b/02_MailClient/src/net/hypki/mailclient/db/sql/MySQLDB.java
@@ -0,0 +1,22 @@
+package net.hypki.mailclient.db.sql;
+
+import net.hypki.mailclient.db.Db;
+
+import java.io.IOException;
+
+public class MySQLDB implements Db {
+    @Override
+    public void save(String key, Object value) throws IOException {
+        // 1. opening a client to a real databse
+        // 2. put object to real database
+        // 3. check for errors
+    }
+
+    @Override
+    public Object get(String key) {
+        // 1. open a client to a database
+        // 2. return data from DB
+        // 3. convert to Object and return it
+        return null;
+    }
+}
diff --git a/02_MailClient/src/net/hypki/mailclient/model/Mail.java b/02_MailClient/src/net/hypki/mailclient/model/Mail.java
new file mode 100644
index 0000000..388a518
--- /dev/null
+++ b/02_MailClient/src/net/hypki/mailclient/model/Mail.java
@@ -0,0 +1,57 @@
+package net.hypki.mailclient.model;
+
+import java.io.IOException;
+
+public class Mail extends ModelObject {
+    private String id = null;
+    private String title = null;
+    private String from = null;
+    private String to = null;
+
+    public Mail() {
+
+    }
+
+    @Override
+    public void validate() throws IOException, IllegalArgumentException {
+        // if `to` mail is incorrect then throw exception
+        if (!to.contains("@"))
+            throw new IOException("bbbbbb");
+    }
+
+    public String getTitle() {
+        // additions
+        // someFunction()
+
+        return title;
+    }
+
+    public void setTitle(String newTitle) {
+
+        this.title = newTitle;
+    }
+
+    public String getFrom() {
+        return from;
+    }
+
+    public void setFrom(String from) {
+        this.from = from;
+    }
+
+    public String getTo() {
+        return to;
+    }
+
+    public void setTo(String to) {
+        this.to = to;
+    }
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+}
diff --git a/02_MailClient/src/net/hypki/mailclient/model/ModelObject.java b/02_MailClient/src/net/hypki/mailclient/model/ModelObject.java
new file mode 100644
index 0000000..2baa78c
--- /dev/null
+++ b/02_MailClient/src/net/hypki/mailclient/model/ModelObject.java
@@ -0,0 +1,7 @@
+package net.hypki.mailclient.model;
+
+import java.io.IOException;
+
+public abstract class ModelObject {
+    public abstract void validate() throws IOException, IllegalArgumentException;
+}
diff --git a/02_MailClient/src/net/hypki/mailclient/model/User.java b/02_MailClient/src/net/hypki/mailclient/model/User.java
new file mode 100644
index 0000000..a696d57
--- /dev/null
+++ b/02_MailClient/src/net/hypki/mailclient/model/User.java
@@ -0,0 +1,36 @@
+package net.hypki.mailclient.model;
+
+import java.io.IOException;
+
+public class User extends ModelObject {
+    private String email = null;
+
+    private String name = null;
+
+    public User() {
+
+    }
+
+    @Override
+    public void validate() throws IOException, IllegalArgumentException {
+        // if `to` mail is incorrect then throw exception
+        if (!email.contains("@"))
+            throw new IOException("bbbbbb");
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}
diff --git a/02_MailClient/src/net/hypki/mailclient/view/MainUI.java b/02_MailClient/src/net/hypki/mailclient/view/MainUI.java
new file mode 100644
index 0000000..7e13c03
--- /dev/null
+++ b/02_MailClient/src/net/hypki/mailclient/view/MainUI.java
@@ -0,0 +1,27 @@
+package net.hypki.mailclient.view;
+
+import net.hypki.mailclient.db.Db;
+import net.hypki.mailclient.db.sql.MySQLDB;
+import net.hypki.mailclient.model.Mail;
+
+import javax.activation.MailcapCommandMap;
+
+public class MainUI {
+
+    private Db database = null;
+
+    public MainUI() {
+        database = new MySQLDB();
+    }
+
+    public void showMainDialog() {
+        // show UI
+
+        while (true) {
+            // check evey 5 mins for new mails
+
+            Mail newMail = new Mail();
+            database.save(newMail.getId(), newMail);
+        }
+    }
+}