diff --git a/src/java/davmail/exchange/ExchangeSession.java b/src/java/davmail/exchange/ExchangeSession.java
index bf285b71..12784f9b 100644
--- a/src/java/davmail/exchange/ExchangeSession.java
+++ b/src/java/davmail/exchange/ExchangeSession.java
@@ -130,24 +130,75 @@ public class ExchangeSession {
         dateFormatter = new java.text.SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z", Locale.ENGLISH);
     }
 
+    /**
+     * Update http client configuration (proxy)
+     *
+     * @param httpClient current Http client
+     */
+    protected void configureClient(HttpClient httpClient) {
+        String enableProxy = Settings.getProperty("davmail.enableProxy");
+        String proxyHost = null;
+        String proxyPort = null;
+        String proxyUser = null;
+        String proxyPassword = null;
+
+        if ("true".equals(enableProxy)) {
+            proxyHost = Settings.getProperty("davmail.proxyHost");
+            proxyPort = Settings.getProperty("davmail.proxyPort");
+            proxyUser = Settings.getProperty("davmail.proxyUser");
+            proxyPassword = Settings.getProperty("davmail.proxyPassword");
+        }
+
+        // configure proxy
+        if (proxyHost != null && proxyHost.length() > 0) {
+            httpClient.getHostConfiguration().setProxy(proxyHost, Integer.parseInt(proxyPort));
+            if (proxyUser != null && proxyUser.length() > 0) {
+                // detect ntlm authentication (windows domain name in user name)
+                int backslashindex = proxyUser.indexOf("\\");
+                if (backslashindex > 0) {
+                    httpClient.getState().setProxyCredentials(null, proxyHost,
+                            new NTCredentials(proxyUser.substring(backslashindex + 1),
+                                    proxyPassword, null,
+                                    proxyUser.substring(0, backslashindex)));
+                } else {
+                    httpClient.getState().setProxyCredentials(null, proxyHost,
+                            new UsernamePasswordCredentials(proxyUser, proxyPassword));
+                }
+            }
+        }
+
+    }
+
+    public void checkConfig() throws IOException {
+        try {
+            String url = Settings.getProperty("davmail.url");
+
+            // create an HttpClient instance
+            HttpClient httpClient = new HttpClient();
+            configureClient(httpClient);
+
+            // get webmail root url (will follow redirects)
+            HttpMethod testMethod = new GetMethod(url);
+            int status = httpClient.executeMethod(testMethod);
+            testMethod.releaseConnection();
+            logger.debug("Test configuration status: " + status);
+            if (status != HttpStatus.SC_OK) {
+                throw new IOException("Unable to connect to OWA at " + url + ", status code " +
+                        status + ", check configuration");
+            }
+
+        } catch (Exception exc) {
+            logger.error("DavMail configuration exception: \n"+exc.getMessage(), exc);
+            throw new IOException("DavMail configuration exception: \n"+exc.getMessage(), exc);
+        }
+
+    }
+
     public void login(String userName, String password) throws Exception {
         try {
             String url = Settings.getProperty("davmail.url");
-            String enableProxy = Settings.getProperty("davmail.enableProxy");
-            String proxyHost = null;
-            String proxyPort = null;
-            String proxyUser = null;
-            String proxyPassword = null;
-
-            if ("true".equals(enableProxy)) {
-                proxyHost = Settings.getProperty("davmail.proxyHost");
-                proxyPort = Settings.getProperty("davmail.proxyPort");
-                proxyUser = Settings.getProperty("davmail.proxyUser");
-                proxyPassword = Settings.getProperty("davmail.proxyPassword");
-            }
 
             // get proxy configuration from setttings properties
-
             URL urlObject = new URL(url);
             // webdavresource is unable to create the correct url type
             HttpURL httpURL;
@@ -176,23 +227,7 @@ public class ExchangeSession {
             // do not send basic auth automatically
             httpClient.getState().setAuthenticationPreemptive(false);
 
-            // configure proxy
-            if (proxyHost != null && proxyHost.length() > 0) {
-                httpClient.getHostConfiguration().setProxy(proxyHost, Integer.parseInt(proxyPort));
-                if (proxyUser != null && proxyUser.length() > 0) {
-                    // detect ntlm authentication (windows domain name in user name)
-                    int backslashindex = proxyUser.indexOf("\\");
-                    if (backslashindex > 0) {
-                        httpClient.getState().setProxyCredentials(null, proxyHost,
-                                new NTCredentials(proxyUser.substring(backslashindex + 1),
-                                        proxyPassword, null,
-                                        proxyUser.substring(0, backslashindex)));
-                    } else {
-                        httpClient.getState().setProxyCredentials(null, proxyHost,
-                                new UsernamePasswordCredentials(proxyUser, proxyPassword));
-                    }
-                }
-            }
+            configureClient(httpClient);
 
             // get webmail root url (will follow redirects)
             // providing credentials
diff --git a/src/java/davmail/pop/PopConnection.java b/src/java/davmail/pop/PopConnection.java
index c02a682a..c7e8cb48 100644
--- a/src/java/davmail/pop/PopConnection.java
+++ b/src/java/davmail/pop/PopConnection.java
@@ -4,10 +4,11 @@ import davmail.AbstractConnection;
 import davmail.DavGatewayTray;
 import davmail.exchange.ExchangeSession;
 
-import java.net.Socket;
-import java.net.UnknownHostException;
-import java.util.*;
 import java.io.IOException;
+import java.net.Socket;
+import java.util.Date;
+import java.util.List;
+import java.util.StringTokenizer;
 
 /**
  * Dav Gateway pop connection implementation
@@ -53,6 +54,8 @@ public class PopConnection extends AbstractConnection {
         StringTokenizer tokens;
 
         try {
+            session = new ExchangeSession();
+            session.checkConfig();
             sendOK("DavMail POP ready at " + new Date());
 
             for (; ;) {
@@ -93,16 +96,10 @@ public class PopConnection extends AbstractConnection {
                         } else {
                             password = tokens.nextToken();
                             try {
-                                session = new ExchangeSession();
                                 session.login(userName, password);
                                 messages = session.getAllMessages();
                                 sendOK("PASS");
                                 state = AUTHENTICATED;
-                            } catch (UnknownHostException e) {
-                                DavGatewayTray.error("Connection failed", e);
-                                sendERR("Connection failed : " + e + " " + e.getMessage());
-                                // close connection
-                                break;
                             } catch (Exception e) {
                                 DavGatewayTray.error("Authentication failed", e);
                                 sendERR("authentication failed : " + e + " " + e.getMessage());
@@ -185,7 +182,12 @@ public class PopConnection extends AbstractConnection {
                 os.flush();
             }
         } catch (IOException e) {
-            DavGatewayTray.error("Exception handling client", e);
+            DavGatewayTray.error(e.getMessage());
+            try {
+                sendERR(e.getMessage());
+            } catch (IOException e2) {
+                DavGatewayTray.debug("Exception sending error to client", e2);
+            }
         } finally {
             try {
                 client.close();
diff --git a/src/java/davmail/smtp/SmtpConnection.java b/src/java/davmail/smtp/SmtpConnection.java
index 97d25ae9..dbd0eeee 100644
--- a/src/java/davmail/smtp/SmtpConnection.java
+++ b/src/java/davmail/smtp/SmtpConnection.java
@@ -31,6 +31,8 @@ public class SmtpConnection extends AbstractConnection {
 
 
         try {
+            session = new ExchangeSession();
+            session.checkConfig();
             sendClient("220 DavMail SMTP ready at " + new Date());
             for (; ;) {
                 line = readClient();
@@ -118,7 +120,12 @@ public class SmtpConnection extends AbstractConnection {
                 os.flush();
             }
         } catch (IOException e) {
-            DavGatewayTray.error("Exception handling client",e);
+            DavGatewayTray.error(e.getMessage());
+            try {
+                sendClient("500 "+e.getMessage());
+            } catch (IOException e2) {
+                DavGatewayTray.debug("Exception sending error to client", e2);
+            }
         } finally {
             try {
                 client.close();
diff --git a/src/test/davmail/exchange/TestExchangeSession.java b/src/test/davmail/exchange/TestExchangeSession.java
index 08f16913..ed1b0506 100644
--- a/src/test/davmail/exchange/TestExchangeSession.java
+++ b/src/test/davmail/exchange/TestExchangeSession.java
@@ -14,6 +14,7 @@ public class TestExchangeSession {
         ExchangeSession session = new ExchangeSession();
         // test auth
         try {
+            session.checkConfig();
             session.login(argv[1], argv[2]);
 
             ExchangeSession.Folder folder = session.selectFolder(argv[3]);