why are the suppliers invoices I forward to quickbooks online being returned saying can't be read ?

To help us narrow this down, could you let us know if there is a specific error code included in that message?

Usually, when QuickBooks says a document "can't be read," it comes down to a few file requirements. Please double-check that the forwarded invoices meet these guidelines:

• File Format: The attachments must be in PDF, JPEG, JPG, GIF, or PNG format.
• File Size: Each attachment must be between 46 KB and 20 MB. If a file is too small (low-resolution), the system's text scanner cannot read it.
• Image Quality: Ensure the text isn't blurry, cut off, or heavily shadowed.

You can absolutely send multiple images in a single email, as long as the total size stays within that 20 MB limit.

For a full walkthrough on troubleshooting these attachments, please check out this article: Forward images of receipts and bills to QuickBooks.

If your files already meet all of these specs and are still being returned, please let us know so we can investigate further.