OE attachment blocked

When certain e-mail senders send e-mail with an attachment I get the e-mail message, but the attachment is blocked. In the attachment block of the message the following message appears:
OE removed access to the following unsafe attachment in your mail: C-OHIO.xls, F-OHIO.xls.
The attachments are from the Wells Fargo Bank. They are mortgage rate sheets. Can anyone help me with this?

frenchfries