This problem is fixed in the latest version of Eudora.  You can get at copy at http://www.eudora.com/pro_email/updaters.html.

>Have any of you encountered the below warning message?  So far, it appears
>to be isolated to only three users who are each using Eudora 4.1 to send
>email to our lists.  However, there are other users who are using the same
>version of this email client without producing the error.
>
>In addition, we've now discovered that one user can send email to the same
>list and only produce the error intermittently.  The messages are always
>sent the same way, but with different results; sometimes with the warning
>message and other times without.
>
>If any of you have encountered this and know of a remedy, please
>share.  Actually, even if you don't know of a remedy but care to share what
>you've tried in an effort to rid yourselves of the messages, that would be
>nice as well.  It could possibly save me some steps.
>
>>>Comments:     RFC822 error: <W> MESSAGE-ID field duplicated. Last occurrence
>>>              was retained.

--
Bill Verity - 814-865-4758  Fax: 814-863-7049
Postmaster & Listserv maintainer
Center for Academic Computing, Penn State University
At the office - on my Mac, of course ;-)

As Bugs said to Woody, "Here's your hickory daiquiri, Doc."