Word Attachments showing up unreadable in for recipient

[Andy Harlan]

We send a newsletter by email to multiple recipients and
some people are unable to read the attachment. The
attachment shows up as mixed symbols and letters instead
of the document. This only happens with certain end
users. Most recipients can read it fine. We have tried
sending Plain text and Rich text with the same result.

Have any ideas why this is happening?

Thanks.