* CAPABILITY IMAP4 IMAP4rev1
This server claims to implement all of IMAP4 (RFC 1730) and all of IMAP4rev1 (RFC 3501 nee 2060).
If, as you report, this server rejects the PARTIAL command then it is not RFC 1730 compliant and it is broken. A server which rejects the PARTIAL command MUST NOT advertise the IMAP4 capability.
If, as you report, this server rejects <xx.yy> style partial fetching then it is not RFC 3501 (nee 2060) compliant and it is broken. A server which rejects <xx.yy> style partial fetching MUST NOT advertise the IMAP4rev1 capability.
Since this server is broken, there is little point in discussing how to support it in your client. It is completely unpredictable what this server does and does not do.
If you want to have a fall back (e.g. the equivalent of Pine's /loser mailbox specifier switch), consider RFC 1176 (IMAP2); but only if the user specifies a "this server is known to be broken" flag.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
