I'd agree with Paul. They have access to the RoundCube code with some minor restrictions. What they're looking for here is a way to remove the GPL restrictions, not improve the platform. They can see the way that RoundCube approaches particular problems, but what the offer says is that they basically want to buy out RoundCube and remove their competition. Notice the complete lack of any kind of on-going support (in the monetary sense): "offer you a reasonable fee to purchase the license of Roundcube, the site, and for the effort you have contributed to the project."
"you to consult our company in Australia for 1-3 months on the development of @Mail and merging the two products for the open source offering"
These are not business deals, it's a buyout, pure & simple.
Paul Waring wrote:
Their home page reads:
"Filtering out the white noise of growing open-source options, @Mail is a reliable and complete messaging platform that includes full source code for complete control."
Doesn't sound as if they're terribly keen on open source to me...
Anyway, if they want the advantages/features of Roundcube, they can take them, provided they abide by the terms of the GPL. I don't see why they'd have to license the name or buy the domain if they just want to improve and open source their existing product. There's also nothing to stop them offering commercial support for Roundcube if they want, as far as I'm aware that's perfectly legitimate under the GPL.
Paul