Nokia :: X6 - Is SMTP Authentication Impossible?

I want to use an SMTP server which is not provided by the operator (network or broadband). The only form of authentication catered for seems to be "POP before SMTP" where you have to authorise sending using the same login as you first receive with.

Settings I see are:

Incoming : there is no field for remote mailbox address - weird?
Outgoing: there IS a field for remote mailbox address - why? The username and password fields provided seem to relate to this remote mailbox address, not to the SMTP server. (Anyway, they already exist in incoming settings)
E.g. I can receive from my remote mailbox fine. That's "me@tiscali.co.uk" I can't authenticate using the "smtp.o2.co.uk" server to send using my address of "me@tiscali.co.uk" as there is nowhere to enter my o2 authentication details. (I can send unauthorised to o2 addresses)

The above example works fine in Profimail email client and with Profimail I can send emails carrying the "me@tiscali.co.uk" address with o2 authentication via the o2 SMTP server by either t-mobile network or by tiscali broadband WLAN to any of various test addresses.