I tried to activate email in my brand new w800i but failed on the encryption part - "TLS/SSL unknown certificate authority". My email provider regards itself big enough to have their own certificate infrastructure (the Swedish Universities act as their own CA) and, of course, the phone does not know about this. Sadly, there is no way to enter or enable a new CA in the phone. Conclusion: no email for me.
SonyEricsson, please look into this...
Update: I spoke to SonyEricsson Support, and they said they already had made a request for self-signed certificates, but don't know if/when that will be added. A bit sad, as this will hinder quite a lot of services. In theory, this will prevent all Swedish University staff from using secure services.