[SOLVED] How to setup a 'Send e-mail' function?

Can somebody help me?

I have a trouble with user-to-user emails in Community Builder. I guess this function is in the core, so it is shown in a CB menu by default and requires no additional plugins. But it doesn't work on my site. When trying to send an email I get a error message. Though I'm pretty sure that both sender's and receiver's emails are set correctly (since I've set these by myself for these 2 testing accounts).

Does anybody have an idea about how to make in work?
Thanks in advance!

Technical info:
Joomla 2.5.6, CB 1.8.1, website www.instapoker.tv (a can give you login details if needed).

I get a error message

What is the error?

Have you tried CB > User Management > Mass Mailer to ensure emails even send?

I use a russian version - the error is 'Отправка Вашего письма не прошла! Пожалуйста попытайтесь еще раз.' . Strict translation is 'Your email is not sent! Please try again.'

Let me check the mass mailers, I'll report you shortly.

OK Kyle, I've just checked the mass mailer - it works fine. I've sent a mass mail to 2 testing users, it is delivered to both mailboxes.

Do registration emails send successfully? Please grab the original string that is being translated so I can see exactly what's triggering that string. I'm guessing the 10 emails per hour limit is being hit (I think that's the limit, maybe it's per day?).

Yes, everything's alright with the registration emails. Just created a new user to ensure.

I never heard about any 'per hour/ per day' limitations for a number of emails. Could you tell me where I should check it?

The original error message is: _UE_SENTEMAILFAILED . In English it is: Your email failed to send! Please try again.