[Imap-protocol] changed capabilities after login

Arnt Gulbrandsen arnt at gulbrandsen.priv.no
Fri Sep 1 02:49:29 PDT 2006

IMO, the Mirapoint server is at fault. What it does is legal according
to the RFC, I suppose, but it's not a great win wrt. interoperability.

If the Mirapoint proxy advertises any capabilities that the proxied
server does not support, the Mirapoint proxy should deal with that.
Hiding being a part of the RFC that most people miss isn't acceptable.
One thing it could do is issue CAPABILITY on its own and report the
changed capability list in the response to LOGIN, or in any random
untagged OK.

(Many years ago, when I worked at a company that no longer exists, I
wrote an IMAP proxy. It had a bug much like this. Legal according to
the RF, broke clients. The only difference is that my bug had a good
reason and was useful.)


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