What does the envelope sign after the author name mean? I'm in the process of writing a paper for an upcoming conference. The conference provides a LaTeX template which can be found here: Information for Authors of Springer Computer Science Proceedings.

Looking at the proceedings of the previous years I noticed a little envelope after the name of the first authors.



However, I was not able to figure out what it means. So my question is what is the meaning of the little envelope after the name of the first author?
With Springer journals, the envelope simply indicates that they are the nominated corresponding author for the paper. 

Sources: this forum topic and a Springer 'Instructions to Authors' PDF.