IMP Single Signon

Notes on using kerberos/cosign or other single-signon solutions for IMP.

One option is to have the IMAP server just trust IMP.

Cyrus proxyd since 2.2.9 has a -N switch to allow login without authentication. IMP just passes along REMOTE_USER as provided by Cosign, etc. If don't know if any other IMAP servers have similar options.