jm2e on BB 88800 problem

[jurg]

We have a BB 8800 (software version 4.2) on which we installed the zimbrame client. However, after filling in our server name and user account we always get to see 'malformed address'. Looking at the zimbra mailbox.log, we do not see any login attempt.
Anyone seen this before?
We run Release 5.0.1_GA_1902.UBUNTU6 UBUNTU6 NETWORK edition.