I had the exact same problem trying to use a webservice to create new users and afterwards sending them a registration message. The Currentportalsettings then just doesn't work. Btw, I do use iweb but I don't see how that solves the problem getting the portalsettings for the sendmail method.

However, the following (using the overload on the Portalsettings constructor) seems to work for me as it doesn't seem to use the httpcontext.Current:

Dim objPortalController As New PortalController
Dim objPortalInfo As PortalInfo = objPortalController.GetPortal(portalID)
Dim objPortalAliasInfo As New PortalAliasInfo
objPortalAliasInfo.PortalID = portalID
Dim portalsettings As New PortalSettings(objPortalInfo.HomeTabId, objPortalAliasInfo)