Yahoo IMAP UID+ COPYUID broken?

Question

It seems the COPYUID functionality in Yahoo's IMAP UID+ is not at all working. e.g. our task that moves messages receives the trace:

S: C32 OK [COPYUID 1348693428 122572 122552] COPY completed

We log into the box and verify uidvalidity:

S: * OK [UIDVALIDITY 1348693428] UIDs valid

However the fetch fails:

C: C6 UID FETCH 122552 (BODY.PEEK[] UID)
S: C6 OK UID FETCH completed

I'm wondering if anyone has experienced similar frustrations over Yahoo UID+, if there is a workaround, I have an error in my client etc.

Furthermore I am testing this on my personal account and messages are not modified after being copied.

Answer 1

Fwiw several weeks of development on this later I can confidently say yes, it's just flat-out broken and should not be used.