After installing Ubuntu One, I tested it in Thunderbird by sending myself a file. I then got a marketing message at the address I sent it to promoting Ubuntu One. Is that the price to be paid for the free version, or can this be turned off?
Well, I have asked to the Thunderbird team. This cannot be turned off easily, but if you have idea to make it looks better, the relevant code is available here: http://mxr.mozilla.org/comm-release/source/mail/components/compose/content/cloudAttachmentLinkManager.js#330 and developers will be open to comments or tweaks about this code.