Email acting strangely after changing contact address

Hi,
I'm having a strange problem. I recently changed part of my email settings.
In Confirguration>E-Mail Options I changed
Email Address (Displayed to Contact you):from sales@ to [email protected]
Email Address (sent FROM):from sales@ to [email protected]

All the other email settings are pointing to [email protected]

Basically I wanted to set up a different email address for correspondence through the website so a staff member could answer those enquiries, and have all the order confirmation emails come through to my "sales" email address.

Ever since then strange things have been happening in my "sales" address. Spam email, payment confirmation from worldpay and new orders have been coming through as a [New Order] email with an order number below what I started with (when I moved from OSC I kept my order numbers the same so started at 6000, these orders are in the range of 5000-6000). They're also appearing to be dated January/February 2007 although the email headers say otherwise.
The orders that have come through this way have the correct date and order number in my shop admin and payments have gone through successfully.

Any ideas why this is happening?

I should add that the incorrect order number in order confirmation emails seems to be happening sporadically. I just got a new order through with the correct order number.