Try to register, and see that it is impossible ..

Hello guys, I worked with Elgg in 2011 on a particular project, I used the version 1.7.1. I had to stop my project due to professional reasons.

Today, three years later, I'm back to work with Elgg. But now I use the version 1.8.

I don't know for what reason, but it is IMPOSSIBLE to register a new user in my social network, when trying to complete the registration, email is not sent, and the login is impossible to be done ...

This is no problem related to themes which I used, because I have disabled them all, and registration remains impossible ....

This is my site:

Try to register and see that it is impossible ..

You know how to change it?