V 9.2 rejecting Posteo credentials

Initial setup
1

I recently set up a Posteo account and want to add it to EM Client v.9.2, but the client keeps rejecting my details, saying ‘authentication failed’. I believe I have the correct IMAP/SMTP details:

  • Server: posteo.de
  • Incoming: Port 993, using SSL/TLS on special port (legacy)
  • Outgoing: Port 465, using SSL/TLS on special port (legacy), authentication required

I believe this matches the instructions Posteo provided for setting up the email in an email client, but it still can’t authenticate. Is it possible I’ve misread the instructions? Any advice would be appreciated, thank you.

2

Those mail server settings look correct.

I don’t know if your account uses an OAuth token (passwordless) login ?

Have you tried adding both ways using the Automatic setup wizard, and also adding it manually via “Add account / Mail / Other” ?

If you have tried adding both ways with your email address and password “and you can login ok to your mailbox online”, then could be you possibly need an eg: Generated app password from your online mail account instead of your normal email password.

Or could be you might need to eg: enable third party mail client access within your online mail account.

So check also with your mailbox online technical support staff to see if you do need any app password or need to enable third party mail client access as some mailboxes do require them.

Lastly see if there is also “anymore obvious errors in the Operations Log” via clicking the dropdown on the right of Refresh top left. Then click “Show Operations” and click the “Log tab”.

3

Hi,

Thanks for the reply! I’ve done what you’ve suggested, and I can’t find anything about an app password or enabling third-party mail client access on Posteo. The relevant part of the log is below:

7:40:27 PM [EMAIL ADDRESS] IMAP Synchronizing folder list
7:41:08 PM [EMAIL ADDRESS] [IMAP] MailClient.Accounts.AbortedException: Connection could not be created while going offline.
            ---> System.OperationCanceledException: Connect operation was cancelled
            ---> MailClient.Imap.Base.ByeException: Connection is closed
              at MailClient.Imap.Base.Connection.RunCommandAsync(Command command, Func`3 notificationCallback)
              at MailClient.Imap.Base.Connection.LoginAsync(String name, String password)
              at MailClient.Protocols.Imap.ConnectionPoolEntry.ConnectInternalAsync(CancellationToken cancellationToken)
              --- End of inner exception stack trace ---
              at MailClient.Protocols.Imap.ConnectionPoolEntry.ConnectInternalAsync(CancellationToken cancellationToken)
              at MailClient.Protocols.Imap.ConnectionPool.AcquireConnectionAsync(Folder mailFolder, Boolean noSelect)
              --- End of inner exception stack trace ---
              at MailClient.Protocols.Imap.ConnectionPool.AcquireConnectionAsync(Folder mailFolder, Boolean noSelect)
              at MailClient.Protocols.Imap.ConnectionContext.CreateContextAsync(ImapAccount account)
              at MailClient.Protocols.Imap.ImapFolderSynchronizer.ListFoldersAsync(IListFoldersProgress progress, Folder homeFolder, CancellationToken cancellationToken)
              at MailClient.Protocols.Imap.ImapFolderSynchronizer.GetFolderList(IListFoldersProgress progress, Folder homeFolder, CancellationToken cancellationToken)
              at MailClient.Protocols.Common.FolderSynchronizer.<>c__DisplayClass16_0.<EnqueueGetFolderList>b__0(WorkerStatus status, CancellationToken cancellationToken)
              at MailClient.Protocols.Imap.ImapActionCommand.<>c__DisplayClass11_0.<.ctor>b__0(WorkerStatus ws, CancellationToken ct)
              at MailClient.Protocols.Imap.ImapActionCommand.ExecuteInternalSync(WorkerStatus status)
              at MailClient.Protocols.Imap.ImapActionCommand.Execute(WorkerStatus status)
              at MailClient.Commands.Command.Process(WorkerStatus status)
             EnqueuedStackTrace =
                  at MailClient.Protocols.Common.FolderSynchronizer.GoOnlinePre()
                  at MailClient.Protocols.Imap.ImapFolderSynchronizer.GoOnlinePre()
                  at MailClient.Protocols.Imap.ImapAccount.GoOnlineInt()
                  at MailClient.Protocols.Common.AccountBase.ChangeOnlineState(Boolean online, OfflineReason offlineReason)
                  at MailClient.Protocols.Common.AccountBase.GoOnline()
                  at MailClient.Accounts.AccountList.<>c__DisplayClass24_0.<SetOnlineState>b__1(IAccount account)
                  at System.Threading.Tasks.Parallel.<>c__DisplayClass44_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int32 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
                  at System.Threading.Tasks.TaskReplicator.Replica`1.ExecuteAction(Boolean& yieldedBeforeCompletion)
                  at System.Threading.Tasks.TaskReplicator.Replica.Execute()
                  at System.Threading.Tasks.TaskReplicator.Replica.<>c.<.ctor>b__4_0(Object s)
                  at System.Threading.Tasks.Task.InnerInvoke()
                  at System.Threading.Tasks.Task.<>c.<.cctor>b__272_0(Object obj)
                  at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
                  at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
                  at System.Threading.Tasks.Task.ExecuteEntryUnsafe(Thread threadPoolThread)
                  at System.Threading.Tasks.ThreadPoolTaskScheduler.TryExecuteTaskInline(Task task, Boolean taskWasPreviouslyQueued)
                  at System.Threading.Tasks.TaskScheduler.TryRunInline(Task task, Boolean taskWasPreviouslyQueued)
                  at System.Threading.Tasks.Task.InternalRunSynchronously(TaskScheduler scheduler, Boolean waitForCompletion)
                  at System.Threading.Tasks.Task.RunSynchronously(TaskScheduler scheduler)
                  at System.Threading.Tasks.TaskReplicator.Run[TState](ReplicatableUserAction`1 action, ParallelOptions options, Boolean stopOnFirstFailure)
                  at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal](Partitioner`1 source, ParallelOptions parallelOptions, Action`1 simpleBody, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
                  at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
                  at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, Action`1 body)
                  at MailClient.Accounts.AccountList.SetOnlineState(Boolean online, OfflineReason offlineReason, IComparer`1 comparer)
                  at MailClient.Accounts.BindingAccountBase.GoOnline()
                  at MailClient.Accounts.AccountList.<>c__DisplayClass25_0.<AddAccountConfigurations>b__0(IAccountConfiguration accountConfiguration)
                  at System.Threading.Tasks.Parallel.<>c__DisplayClass32_0`2.<ForEachWorker>b__0(Int32 i)
                  at System.Threading.Tasks.Parallel.<>c__DisplayClass19_0`1.<ForWorker>b__1(RangeWorker& currentWorker, Int32 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
                  at System.Threading.Tasks.TaskReplicator.Replica.Execute()
                  at System.Threading.Tasks.TaskReplicator.Replica.<>c.<.ctor>b__4_0(Object s)
                  at System.Threading.Tasks.Task.InnerInvoke()
                  at System.Threading.Tasks.Task.<>c.<.cctor>b__272_0(Object obj)
                  at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
                  at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
                  at System.Threading.Tasks.Task.ExecuteEntryUnsafe(Thread threadPoolThread)
                  at System.Threading.Tasks.ThreadPoolTaskScheduler.TryExecuteTaskInline(Task task, Boolean taskWasPreviouslyQueued)
                  at System.Threading.Tasks.TaskScheduler.TryRunInline(Task task, Boolean taskWasPreviouslyQueued)
                  at System.Threading.Tasks.Task.InternalRunSynchronously(TaskScheduler scheduler, Boolean waitForCompletion)
                  at System.Threading.Tasks.Task.RunSynchronously(TaskScheduler scheduler)
                  at System.Threading.Tasks.TaskReplicator.Run[TState](ReplicatableUserAction`1 action, ParallelOptions options, Boolean stopOnFirstFailure)
                  at System.Threading.Tasks.Parallel.ForWorker[TLocal](Int32 fromInclusive, Int32 toExclusive, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Func`4 bodyWithLocal, Func`1 localInit, Action`1 localFinally)
                  at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](TSource[] array, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
                  at System.Threading.Tasks.Parallel.ForEachWorker[TSource,TLocal](IEnumerable`1 source, ParallelOptions parallelOptions, Action`1 body, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
                  at System.Threading.Tasks.Parallel.ForEach[TSource](IEnumerable`1 source, Action`1 body)
                  at MailClient.Accounts.AccountList.AddAccountConfigurations(IEnumerable`1 accountConfigurations, Boolean callbacks)
                  at MailClient.Accounts.AccountList.AccountConfigurations_CollectionChanged(Object sender, NotifyCollectionChangedEventArgs`1 e)
                  at System.EventHandler`1.Invoke(Object sender, TEventArgs e)
                  at MailClient.Accounts.AccountManager.Add(IAccountConfiguration item)
                  at MailClient.UI.Forms.wizardInitial.wizard1_CloseFromFinish(Object sender, CancelEventArgs e)
                  at MailClient.UI.Wizard.Wizard.finish()
                  at MailClient.UI.Wizard.Wizard.Next()
                  at MailClient.UI.Wizard.Wizard.btnNext_Click(Object sender, EventArgs e)
                  at System.Windows.Forms.Control.OnClick(EventArgs e)
                  at MailClient.Common.UI.Controls.ControlToolStrip.ControlToolStripButton.PerformClick()
                  at MailClient.Common.UI.Controls.ControlToolStrip.ControlToolStripButton.OnMouseUp(MouseEventArgs e)
                  at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
                  at System.Windows.Forms.Control.WndProc(Message& m)
                  at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
                  at System.Windows.Forms.ContainerControl.WndProc(Message& m)
                  at System.Windows.Forms.UserControl.WndProc(Message& m)
                  at MailClient.Common.UI.Controls.NonFlickeringUserControl.WndProc(Message& m)
                  at MailClient.Common.UI.Controls.AutomationViewUserControl.WndProc(Message& m)
                  at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
                  at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
                  at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, WM msg, IntPtr wparam, IntPtr lparam)
                  at Interop.User32.DispatchMessageW(MSG& msg)
                  at System.Windows.Forms.Application.ComponentManager.Interop.Mso.IMsoComponentManager.FPushMessageLoop(UIntPtr dwComponentID, msoloop uReason, Void* pvLoopData)
                  at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(msoloop reason, ApplicationContext context)
                  at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(msoloop reason, ApplicationContext context)
                  at System.Windows.Forms.Application.RunDialog(Form form)
                  at System.Windows.Forms.Form.ShowDialog(IWin32Window owner)
                  at MailClient.UI.Forms.wizardInitial.NewAccount(IWin32Window parent)
                  at MailClient.UI.Forms.formAccounts.buttonNewAccount_Click(Object sender, EventArgs e)
                  at System.Windows.Forms.Control.OnClick(EventArgs e)
                  at MailClient.Common.UI.Controls.ControlToolStrip.ControlToolStripButton.PerformClick()
                  at MailClient.Common.UI.Controls.ControlToolStrip.ControlToolStripButton.OnMouseUp(MouseEventArgs e)
                  at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
                  at System.Windows.Forms.Control.WndProc(Message& m)
                  at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
                  at System.Windows.Forms.ContainerControl.WndProc(Message& m)
                  at System.Windows.Forms.UserControl.WndProc(Message& m)
                  at MailClient.Common.UI.Controls.NonFlickeringUserControl.WndProc(Message& m)
                  at MailClient.Common.UI.Controls.AutomationViewUserControl.WndProc(Message& m)
                  at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
                  at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
                  at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, WM msg, IntPtr wparam, IntPtr lparam)
                  at Interop.User32.DispatchMessageW(MSG& msg)
                  at System.Windows.Forms.Application.ComponentManager.Interop.Mso.IMsoComponentManager.FPushMessageLoop(UIntPtr dwComponentID, msoloop uReason, Void* pvLoopData)
                  at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(msoloop reason, ApplicationContext context)
                  at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(msoloop reason, ApplicationContext context)
                  at System.Windows.Forms.Application.Run(ApplicationContext context)
                  at MailClient.Program.<>c.<Main>b__187_3()
                  at System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme)
                  at System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj)
                  at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
                  at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
                  at System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme)
                  at System.Windows.Forms.Control.InvokeMarshaledCallbacks()
                  at System.Windows.Forms.Control.WndProc(Message& m)
                  at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
                  at System.Windows.Forms.ContainerControl.WndProc(Message& m)
                  at System.Windows.Forms.Form.WndProc(Message& m)
                  at MailClient.Common.UI.Forms.BaseForm.WndProc(Message& m)
                  at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
                  at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
                  at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, WM msg, IntPtr wparam, IntPtr lparam)
                  at Xilium.CefGlue.Interop.libcef.run_message_loop()
                  at MailClient.Program.Main(String[] args)
             GUIStatus_Exception_Reported = True

I admit I have no idea what any of this means, so if you could provide some insights, I’d appreciate it. Thanks again!

4

I carn’t tell from that log why you are getting authentication failed other than at the start of the log that it shows that “the connection could not be created while going offline”, and then the connection was cancelled. But that wouldn’t be anything to do with authentication failed.

I did however find an eM Client webpage on a Posteo.de mail setup using the “add mail / other” option with different Port and Security policies. So try the below settings with the manual setup.

Note: The username could either be the first part of your email address or the complete email address. So try with both with the same settings.

(How to Setup posteo.de Email)

https://www.emclient.com/setup/posteo.at

IMAP

Server address - posteo.de
Port - 143
Security Policy - Use SSL/TLS if available
Username and Password

SMTP

Server address - posteo.de
Port - 587
Security Policy - Force usage of SSL/TLS
Username and Password

5

Hi again, unfortunately, this didn’t work. I might contact Posteo support to see if they have any advice. If you have any other suggestions, please let me know! Thanks for all your help.

6

Yes apart from contacting Posteo for advise and to check settings etc, if you have a current paid eM Client Pro or Personal version, you can also go to the VIP Support page and login and lodge a support ticket, and include your full operations log with it to be investigated at this end.