Maria, thank you for your replies.
We acted as a sub-contractor, e.g. the Spanish company is also a software development company, they develop custom software products and sell their own software products. They outsourced most of the work on some projects to us. So I believe they cannot be considered as consumers.
Regarding the other signs in your post: yes, we contacted with them by e-mail and delivered all results of our work through Internet: sometimes they downloaded it from our servers (hosted in Russia), sometimes we uploaded it to their servers (hosted in Germany)
So, according to your post, the Spanish jurisdiction is not applicable in my case, is it?
--
Roman