I tried the advice from comp.mail.eudora.ms-windows, and while I convinced Eudora to see the headers of the large messages, it didn't download them even when asked to explicitly. So I asked my brother to resend the photos, and Eudora is again failing to see the message at all.
Even more worrying, I got a call this morning from a friend, answering an email of mine. I'd written to her a couple of days ago; she replied; early this morning I sent a note saying "I haven't heard from you", so she decided to use the phone. We sorted out the matter at hand, but I still haven't see this. And since she was replying to me, odds are good that she had the address right.
If you've written to me and I haven't replied, this may be why.