nnimap alias failing

[leo . butler]

Gnus developed a problem recently accessing an imap server defined in
secondary-select-method. The method is defined as

(nnimap "My.Example"
        (nnimap-authinfo-file "~/.authinfo.gpg")
        (nnimap-address "imap.my.example.com")
        (nnimap-authenticator 'digest-md5)
        (nnimap-server-port 993)
        (nnimap-stream ssl))

If I browse the server via its url, then I am able to do so. On the
other hand, I am getting a message about an non-existent mailbox when I
try to browse the alias.

This seems like a corrupted .newsrc.eld, but I have no idea if that is
true, or how to fix the problem.

Leo