Thanks for responding - I didn't get email notification , hence the delay!
I did as you suggested and upgraded to 5.0.4 but to no avail. The thread you directed me to was interesting but I can't see my way through this one.
I'm currently using OE and leaving messages on the server so I can continue to organise in OE, then I download onto Eudora 5.1 to delete from the server and make any replies. This is a pain!!
Does anyone know if there's an 'identities' facility in Eudora that I haven't found?