---
title: "Error messages from the Mailbox for Employees - Payhawk Help Center"
slug: "error-messages-from-the-receipts-mailbox"
description: "See what the error messages from the Payhawk Mailbox mean, why a forwarded invoice or receipt was not processed, and what to do to send it again correctly."
updated: 2026-10-23T10:38:39Z
published: 2026-10-23T10:38:39Z
canonical: "payhawk.com/error-messages-from-the-receipts-mailbox"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://payhawk.com/help/llms.txt
> Use this file to discover all available pages before exploring further.

# Error messages from the Mailbox

This article explains the most common error messages you can encounter while sending payment documents to the Mailbox in Payhawk.

> [!TIP]
> Regularly monitor the email address from which you're forwarding payment documents (for example, invoices@yourcompany.com). The Mailbox will send error messages to this email address if any issues occur.

## List of error messages

The following table outlines the error messages generated by the Mailbox when payment documents are not processed successfully.

| **Reason** | **Message** | **Next steps** |
| --- | --- | --- |
| Too many attachments | [The email] has more than 40 attachments. We have not processed any of the files. | Send the attachments in separate emails or upload the files directly in the Payhawk portal. |
| Attachment too big | The attachment file size is too big. The combined file size must not exceed 20 MB and a single file must be less than 10 MB. We have not processed any of the files. | Minimize the size of the files and send the email again, or upload the files directly in the Payhawk portal. |
| No attachments | [The email] does not contain supported attachment types - for example, images or PDF documents. | Send an email with at least one and no more than 40 attachments. If no attachments are provided, Payhawk will automatically parse the email body and create a document. |
| Invalid attachment | The attached file does not seem to be a valid file. | Export the file in a [supported file format](/help/supported-file-formats), including PDF, JPG, PNG, or XML. |
| Failed DKIM | Your email does not have a valid DKIM signature. | Validate your email with a [DKIM signature](/help/validating-your-email-with-a-dkim-signature). |
| Failed SPF | The SPF signature of your email is not valid or missing. | Validate your email with an [SPF signature](/help/validating-your-email-with-an-spf-signature). |
| General error | We could not process the email. | If, for example, the attached files couldn't be downloaded due to network issues, [upload the files](https://help.payhawk.com/en/articles/8523786-uploading-and-viewing-invoices-for-purchases) directly in the Payhawk portal. |

## Useful resources

- [FAQ on the Mailbox](/help/faq-on-the-receipts-mailbox)
- [Validating your email with a DKIM signature](/help/validating-your-email-with-a-dkim-signature)
- [Validating your email with an SPF signature](/help/validating-your-email-with-an-spf-signature)