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IMAP: AsposeException: Imap server returned an invalid response: '{0}' The server response was: UID 73


At a customers side our mail archiver program throws an exception when trying to download a signed e-mail. Unfortunately, I do not have access to the e-mail, but nevertheless, I need to know what the following cryptic message means:

AsposeException: Imap server returned an invalid response: '{0}' The server response was:  UID 73)
 ---> ImapException: Imap server returned an invalid response: '{0}' The server response was:  UID 73)
   bei #=q2jSOkNcJfQQ7ugdKgY57RcA5W$Iz9FK7_OcjFZGeQUFw4xpNKYu8W$L7VDsc0D4R.#=qyoNik$EI0F4fgtUMzVWyVg==(Boolean #=q$CtJqMg1vTXdNo4mbge6yg==)
   bei #=q2jSOkNcJfQQ7ugdKgY57RcA5W$Iz9FK7_OcjFZGeQUFw4xpNKYu8W$L7VDsc0D4R.#=q8NynGyfV3hCJz3Ic8D$3lQ==()
--- End of inner exception stack trace ---
   bei #=qw7CHk_003EU3n3Wcg0VEBN6iwAkjY26DEZ7eZhgGUo1jgqSXQ5DmzKHgYdJre9Rl.#=qDnqB$QjOj7UrUZyV6Rcu7A==(IAsyncResult #=qfVLafpoW38MI3FRBD1EbcA==)
   bei #=qw7CHk_003EU3n3Wcg0VEBN6iwAkjY26DEZ7eZhgGUo1jgqSXQ5DmzKHgYdJre9Rl.#=qDnqB$QjOj7UrUZyV6Rcu7A==()
   bei Aspose.Email.Imap.ImapClient.EndFetchMessage(IAsyncResult asyncResult)
   bei Aspose.Email.Imap.ImapClient.FetchMessage(String uniqueId)

Our environment: Aspose.Email, IMAP, Groupwise server

The code that throws the exception:

public bool LoadCurrentMessage()
            LogWriter.writeMessage("Loading current message", LogWriterPrefix, LogLevels.Info, "", Constants.EventLogType.LoadCurrentMessage);
            bool returnValue = false;

                CurrentMessage = Client.FetchMessage(this.CurrentItem.UniqueId);
                CurrentMessage.TimeZoneOffset = TimeZoneInfo.Local.GetUtcOffset(DateTime.UtcNow);

                // Sets mail properties on current item.
                Body = (CurrentMessage.BodyType == BodyContentType.Html) ? CurrentMessage.HtmlBody : CurrentMessage.Body;
                BodyType = (CurrentMessage.BodyType == BodyContentType.Html) ? Constants.MailBodyType.HTML : Constants.MailBodyType.TXT;
                AttachmentCount = CurrentMessage.Attachments.Count;

                returnValue = true;
            catch (Exception ex)
                LogWriter.writeMessage("Error while loading current message: " + ex.ToString(), LogWriterPrefix, LogLevels.Error, "", Constants.EventLogType.LoadCurrentMessage);

            return returnValue;

Best Regards



We regret the inconvenience caused to you. However, the above information is of little help to us for investigating the issue further. Please try it with the latest version of Aspose.Email for .NET i.e. 17.12 and see if it helps. If the issue still persists, please generate IMAP Activity log and share with us. If possible, please take a copy of message from server with MS Outlook and share with us.


The customer sent us an Aspose activity log file, but I cannot find any useful information concerning the error “AsposeException: Imap server returned an invalid response”? What about you?

Attachment: Aspose.Email.IMAP_2018-1-10.log.zip (653.8 KB)

Best regards



Yes, you are right as this log may not be helpful for identifying the issue. Also I have tried this scenario by fetching such mail from my test account but no issue is observed. Could you please share some test account credential where such signed message is available? It will help us to observe the problem and provide assistance accordingly.


If the customer were ready to share a test account, which way would this have to be done?

  1. Do you want to log on remotely to a machine
  2. do you need a test account that is online available?


Option 2 will be fine as we’ll be able to share it, after reproducing the problem at our end, with our Product team for further investigation at their end.


our customer cannot provide test access to the mailbox over internet for reproducing the issues. Would it be possbile for you to connect via TeamViewer to the customer system where the issue can be seen?

Best Regards


That won’t be helpful as we need to reproduce the issue at our end for further investigation. We are sorry but it is necessary to reproduce the issue at our end and get necessary information about the whole scenario that gives raise to such situation.

We have the same issue here: Imap server returned an invalid response: ‘{0}’ The server response was: [COPYUID 147 2252 1]. Any update on this issue?


Thank you for writing to Aspose support team.

You may please create a separate thread and share the test account credentials along with a simple console based application that can be compiled and executed here to observe the problem. It will help us to analyse the issue and provide assistance accordingly.