Email handling not working

I would like to send an email to an user. I fill the email form and I´ve got a message:

"¡Su correo NO ha sido enviado! Por favor, inténtelo de nuevo."

I looked at the logs althought I enabled them and I don´t see any activity. What can be wrong? I have to enable sth? The registration email are sent by te tool.

Enable debug mode and maximum error reporting in Joomla global configuration then retry to see if any errors output. My guess is your mailer configuration in Joomla global configuration is likely incorrect.

This is done and i cannot see anything interesting. The cb sends email when an user is registered.

What can be the problem?

Within CB > Configuration > General set "Emails Sent From" to "Admin Email Address, with Reply-To User Email Address" and see if that helps as your mail server may not like the emails being sent from the actual user sending the email.

This works. So the problem is that i cannot send an email using a gmail account not? Any solution?

It just means you can't send an email to a user from your email address. It will send from your sites email address with the reply-to set to the email address of the user emailing. There is no solution beyond leaving it as instructed above as it's an enforcement made by your mail server. It's basically email spoofing and most mail servers aren't going to allow it.