problem sending

[Bill H.]

a client is having problems sending email from outlook. Some of the replies
she sends out, when received, are missing text and instead is a line like
this:

<< File: ATT00005.txt; charset = Windows-1252 >>

What's causing this behavior, and how is it remedied?

For example, she copied some text from an email I sent to her into outlook
and then added some of her own plain text, and I received the plain text
part, but instead of what she copied, I also received a line like that
above.

Thanks.