Order Confirmation - Plain Text & HTML Version as Attachment

Some of my customers are getting their confirmation e-mails in an interesting fashion. The order confirmation comes in as a blank e-mail with the plain text & HTML versions as attachments, and one blank attachment.



Attachment 1 - Plain Text


Attachment 2 - HTML


Attachment 3 - Blank Attachment


I suspect this has something to do with their email server and/or outlook, but wanted to know if anyone else has ever come across this issue? If so, were you able to resolve it?

Any other thoughts on how to fix this would be greatly appreciated... I would hate for customers to be receiving blank e-mail confirmations on the regular! Most will find the attachments and see their invoice, but not everyone will!