In tray fails to upload

WE HAVE A FORWARD  in OFFICE 365 - emails to our accounts email are forwarded to the myob email in tray email address

If we send an invoice document to  directly to the myob intray email address, it goes in.

If we  send an email WITHOUT  invoice document to accounts and it gets forwarded to the myob account,we get a return

Hi there,

The following files you sent to your In tray didn’t come through:

• there were no attachments. Are you sure you remembered to attach a bill?
  ETC
  
  

If we  send an email WITH  invoice document to accounts and it gets forwarded to the myob account, we get nothing
Nothing in the in tray and NO return email.

so the issue is in myob process after the check for a document included section

This means out email process is getting though the email checks