Validation e-mail not sent

Hello guys!
 

I am using elgg to built a social network for my school paper.

I have a problem while trying to register more test people on my site. The validation e-mail never sent to these accounts i used to register.

Any ideas why this is happening and what can i do for this?

I am using the final version of elgg and i don't have any 3d parties plugin that is blocking the procedure.

 

Thanks in advance,