ErrorMimeContentInvalid when trying to upload multi-part message to Exchange mailbox

Aspose.Email Product Family
1

Hello, I’ve been tasked with consuming millions of EML files into MS Exchange Server mailboxes. This has been going smoothly for the most part, but there is a small percentage of the email messages that throw errors. I can call this to load the file into an object without error:

spose.Email.MailMessage asposeMsg = Aspose.Email.MailMessage.Load(inputFile.FullName, new EmlLoadOptions() { PreserveEmbeddedMessageFormat = true });

But this line throws an exception when the message is trying to be uploaded to the mailbox:

var uploadedMessage = _ExchangeClient.AppendMessage(destinationMailbox.MailboxUris.InboxUri, asposeMsg);

While there seems to be a handful of different “types” of messages that generate this error:

Operation failed. Response code: ErrorMimeContentInvalid, Message text: Invalid MIME content.

I’d like to address the first such cause, which seems to be multi-part email messages in hopes that it sheds light on the other problem cases.

looking at one of the messages in a text editor, I see this:

From: PMDF Internet Messaging <xxxxx_redacted_xxxxxx>
Subject: Dxxxxx_redacted_xxxxxx
To: xxxxx_redacted_xxxxxx
Message-id: <01NX0AOJFEM200IZMBxxxxx_redacted_xxxxxx>
MIME-version: 1.0
Content-type: multipart/report;
 boundary="Boundary_(ID_CpVCMODxYJDgo1zXfr3LXA)"; report-type=delivery-status

--Boundary_(ID_CpVCMODxYJDgo1zXfr3LXA)
Content-type: text/plain; charset=us-ascii
Content-language: EN-US

This report relates to a message you sent with the following header fields:

  Message-id: <973CDF631FDA4360AE18EE825C20B26E@xxxxx_redacted_xxxxxx>
  Date: Mon, 24 Jan 2011 15:34:40 -0600
  From: xxxxx_redacted_xxxxxx
  To: xxxxx_redacted_xxxxxx
  Subject: xxxxx_redacted_xxxxxx[17/54]

Your message cannot be delivered to the following recipients:

  Recipient address: xxxxx_redacted_xxxxxx
  Reason: SMTP transmission failure has occurred
  Diagnostic code: smtp;554 5.6.1 Messages of type message/partial are not supported
  Remote system: dns;xxxxx_redacted_xxxxxx Microsoft ESMTP MAIL Service ready at Mon, 24 Jan 2011 16:16:25 -0600)

I recognize that this is an old email that I’m importing, and specifically for a non-deliverable message, but there are statutes that require that we keep a record of this attempted send of the original multi-part email in addition to the failure responses related to it.

I suspect that I need to somehow re-construct the multiple pieces of this email into a single message, and then try to upload it to the mailbox, but I can’t find any documentation nor avenues within the toolkit that help me accomplish this.

Does anyone have any experience using Aspose-email to re-assemble multi-part messages such that they can be imported into a modern mailbox?

Thanks in advance.

2

@bcarl

To address the ErrorMimeContentInvalid issue when uploading multi-part email messages to an Exchange mailbox, you may need to reconstruct the multi-part message into a single valid MIME message. This is particularly important for messages that contain delivery status notifications or other complex structures.

Here’s a general approach you can take to handle multi-part messages using Aspose.Email:

  1. Load the EML File: You can load the EML file using the MailMessage.Load method, as you have already done.

  2. Check for Multi-part Content: Inspect the loaded message to determine if it contains multi-part content. You can do this by checking the IsMultiPart property of the MailMessage object.

  3. Reconstruct the Message: If the message is multi-part, you may need to manually reconstruct it. This involves iterating through the parts of the message and ensuring that they are properly formatted and combined into a single message.

  4. Upload the Message: Once you have reconstructed the message, you can use the AppendMessage method to upload it to the mailbox.

Here’s a code snippet that demonstrates how to handle this:

using Aspose.Email;
using Aspose.Email.Clients.Exchange;
using Aspose.Email.Mail;

// Load the EML file
MailMessage asposeMsg = MailMessage.Load(inputFile.FullName, new EmlLoadOptions() { PreserveEmbeddedMessageFormat = true });

// Check if the message is multi-part
if (asposeMsg.IsMultiPart)
{
    // Reconstruct the message if necessary
    // This is a simplified example; you may need to handle specific parts based on your requirements
    var reconstructedMessage = new MailMessage();
    foreach (var part in asposeMsg.AlternateViews)
    {
        reconstructedMessage.AlternateViews.Add(part);
    }
    // Set other properties as needed
    reconstructedMessage.Subject = asposeMsg.Subject;
    reconstructedMessage.From = asposeMsg.From;
    reconstructedMessage.To.AddRange(asposeMsg.To);
    
    // Upload the reconstructed message
    var uploadedMessage = _ExchangeClient.AppendMessage(destinationMailbox.MailboxUris.InboxUri, reconstructedMessage);
}
else
{
    // Upload the message directly if it's not multi-part
    var uploadedMessage = _ExchangeClient.AppendMessage(destinationMailbox.MailboxUris.InboxUri, asposeMsg);
}

This code checks if the message is multi-part and reconstructs it accordingly before uploading. Make sure to adjust the reconstruction logic based on the specific structure of your EML files.

If you continue to encounter issues, consider reviewing the documentation on working with messages in Aspose.Email, as it may provide additional insights into handling complex email structures.

Sources:
[1]: How to Save EML File to Office 365 and Exchange Server?

3

Thank you for that - What version of Aspose are you using? asposeMsg.IsMultiPart is not a thing for me. I’m currently on 24.4.0 (about to try upgrading)

4

I upgraded to the most recent version (24.12.0) and still have no IsMultiPart property to refer to.

5

In fact - searching the API reference yields no results when looking for IsMultiPart - have I missed something obvious?

6

Hello @bcarl,

Welcome to our support forum!

Apologies for the confusion caused by incorrect information earlier. I confirm that the IsMultiPart property doesn’t exist.

  1. The error you are encountering indicates that the data you are uploading does not conform to the MIME format. However, the message content you shared as an example does conform to the MIME format, and if it is loaded using:
    MailMessage asposeMsg = Aspose.Email.MailMessage.Load(filename, new EmlLoadOptions() { PreserveEmbeddedMessageFormat = true });
    no exceptions are thrown.
    Could you confirm that the problematic message you are loading from inputFile.FullName indeed contains data in the MIME format? Is there any chance of a mistake in the data?

  2. Additionally, your comment about multi-part messages is a bit unclear. All parts of a multi-part message are contained within a single file, and there is no need to reconstruct the message. Could you clarify what you meant by that?