diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/data/DataLibrus.kt b/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/data/DataLibrus.kt
index d7437d77..139545cc 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/data/DataLibrus.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/data/DataLibrus.kt
@@ -137,6 +137,25 @@ class DataLibrus(app: App, profile: Profile?, loginStore: LoginStore) : Data(app
         get() { mSynergiaSessionIdExpiryTime = mSynergiaSessionIdExpiryTime ?: profile?.getStudentData("accountSIDTime", 0L); return mSynergiaSessionIdExpiryTime ?: 0L }
         set(value) { profile?.putStudentData("accountSIDTime", value) ?: return; mSynergiaSessionIdExpiryTime = value }
 
+
+    /**
+     * A Messages web Session ID (DZIENNIKSID).
+     * Used in endpoints with Messages login method.
+     */
+    private var mMessagesSessionId: String? = null
+    var messagesSessionId: String?
+        get() { mMessagesSessionId = mMessagesSessionId ?: profile?.getStudentData("messagesSID", null); return mMessagesSessionId }
+        set(value) { profile?.putStudentData("messagesSID", value) ?: return; mMessagesSessionId = value }
+    /**
+     * The expiry time for [messagesSessionId], as a UNIX timestamp.
+     * Used in endpoints with Messages login method.
+     * TODO verify how long is the session ID valid.
+     */
+    private var mMessagesSessionIdExpiryTime: Long? = null
+    var messagesSessionIdExpiryTime: Long
+        get() { mMessagesSessionIdExpiryTime = mMessagesSessionIdExpiryTime ?: profile?.getStudentData("messagesSIDTime", 0L); return mMessagesSessionIdExpiryTime ?: 0L }
+        set(value) { profile?.putStudentData("messagesSIDTime", value) ?: return; mMessagesSessionIdExpiryTime = value }
+
     /*     ____  _   _
           / __ \| | | |
          | |  | | |_| |__   ___ _ __
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusMessages.kt b/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusMessages.kt
index 26e3db39..1f6667bf 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusMessages.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusMessages.kt
@@ -4,5 +4,43 @@
 
 package pl.szczodrzynski.edziennik.api.v2.librus.login
 
-class LoginLibrusMessages {
+import pl.szczodrzynski.edziennik.api.v2.*
+import pl.szczodrzynski.edziennik.api.v2.librus.data.DataLibrus
+import pl.szczodrzynski.edziennik.currentTimeUnix
+import pl.szczodrzynski.edziennik.isNotNullNorEmpty
+
+class LoginLibrusMessages(val data: DataLibrus, val onSuccess: () -> Unit) {
+    companion object {
+        private const val TAG = "LoginLibrusMessages"
+    }
+
+    init { run {
+        if (data.profile == null) {
+            data.error(TAG, ERROR_PROFILE_MISSING)
+            return@run
+        }
+
+        if (data.messagesSessionIdExpiryTime-30 > currentTimeUnix() && data.messagesSessionId.isNotNullNorEmpty()) {
+            onSuccess()
+        }
+        else {
+            when (data.loginStore.mode) {
+                LOGIN_MODE_LIBRUS_SYNERGIA -> loginWithCredentials()
+                else -> {
+                    loginWithSynergia()
+                }
+            }
+        }
+    }}
+
+    private fun loginWithCredentials() {
+        if (data.apiLogin == null || data.apiPassword == null) {
+            if (!data.loginMethods.contains(LOGIN_METHOD_LIBRUS_SYNERGIA)) {
+                data.error(TAG, ERROR_LOGIN_METHOD_NOT_SATISFIED)
+                return
+            }
+            data.error(TAG, ERROR_LOGIN_DATA_MISSING)
+            return
+        }
+    }
 }
\ No newline at end of file
diff --git a/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusSynergia.kt b/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusSynergia.kt
index 0134347d..e78cd860 100644
--- a/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusSynergia.kt
+++ b/app/src/main/java/pl/szczodrzynski/edziennik/api/v2/librus/login/LoginLibrusSynergia.kt
@@ -7,7 +7,6 @@ package pl.szczodrzynski.edziennik.api.v2.librus.login
 import com.google.gson.JsonObject
 import im.wangchao.mhttp.Request
 import im.wangchao.mhttp.Response
-import im.wangchao.mhttp.body.MediaTypeUtils
 import im.wangchao.mhttp.callback.JsonCallbackHandler
 import im.wangchao.mhttp.callback.TextCallbackHandler
 import okhttp3.HttpUrl
@@ -34,11 +33,14 @@ class LoginLibrusSynergia(val data: DataLibrus, val onSuccess: () -> Unit) {
             onSuccess()
         }
         else {
-            when (data.loginStore.mode) {
-                LOGIN_MODE_LIBRUS_SYNERGIA -> loginWithSynergia()
-                else -> {
-                    loginWithApi()
-                }
+            if (data.loginMethods.contains(LOGIN_METHOD_LIBRUS_API)) {
+                loginWithApi()
+            }
+            else if (data.apiLogin != null && data.apiPassword != null) {
+                loginWithCredentials()
+            }
+            else {
+                data.error(TAG, ERROR_LOGIN_DATA_MISSING)
             }
         }
     }}
@@ -46,11 +48,7 @@ class LoginLibrusSynergia(val data: DataLibrus, val onSuccess: () -> Unit) {
     /**
      * HTML form-based login method. Uses a Synergia login and password.
      */
-    private fun loginWithSynergia() {
-        if (data.apiLogin == null || data.apiPassword == null) {
-            data.error(TAG, ERROR_LOGIN_DATA_MISSING)
-            return
-        }
+    private fun loginWithCredentials() {
 
     }
 
@@ -58,11 +56,6 @@ class LoginLibrusSynergia(val data: DataLibrus, val onSuccess: () -> Unit) {
      * A login method using the Synergia API (AutoLoginToken endpoint).
      */
     private fun loginWithApi() {
-        if (!data.loginMethods.contains(LOGIN_METHOD_LIBRUS_API)) {
-            data.error(TAG, ERROR_LOGIN_METHOD_NOT_SATISFIED)
-            return
-        }
-
         val onSuccess = { json: JsonObject ->
             loginWithToken(json.getString("Token"))
         }