E-mail client not displaying in-line images

Not sure if this post belongs here, since I've read many accounts now of the same problem among users with various O/S's and e-mail clients.

In my case I'm using WinXP and Eudora e-mail client.

When I (and other victims) login to the ISP's mail server using a (FireFox) web browser the messages and attachments appear fine. When I forward (D/L to my client) some of those messages that I want to archive, the attachments become "broken links" with the famous "red X" in the box. I am able to click on the "broken link" however which takes me to the associated web host.

I've been using the same software for years, and never had this problem until I wiped the drive and re-installed everything about 18 months ago. At first I suspected I was missing a vital update from MS who at that point no longer supported XP. But then I started reading online messages left by various ppl who also suddenly had the same issues.

Looking a bit deeper, I noticed that the e-mails I D/L which do not have issues have different header info than the ones that do not display the attachments correctly.

If the header info does not contain "DKIM-Signature" then the attachments are displayed normally.

If the header info does included "DKIM-Signature" but not the reference to MIME, then the attachments are not displayed normally.

When the header shows "DKIM-Signature" and a reference to MIME then the message appears the same as when viewed on the ISP server.

For 18 months I've tried various fixes including Internet Option settings, Eudora settings, using Outlook instead of Eudora.... nada.

Have any of you folks experienced a similar issue?

Thanks,
Wolf