We haven' only found Gmail to forward emails correctly.  This is not ideal, but we tried many times and only Gmail was managing proper receipt forwarding.  Manually forwarding receipts will not work.  

SWITCHING TO GMAIL AN OPTION?

While I understand it's a big decision, If you decide to move to Gmail, you can go into your other mail program and have all your mail forwarded to a new Gmail address or just manage two emails with an email client that can show you both.  Then, you could use the Gmail rules to auto-forward your receipts to us and Auto Punch your cards.  I understand that is quite a big decision, but wanted to at least give you one way to get this working.  If we hear of any other way to support this we will research it and let you know.