Problems with wp_mail() function

Hello,

I’m using Dekoboko plugin to create contact form at my blog. The form works perfectly (including recaptcha etc) – the only problem is that when I fill in all information and press submit, I get this error:

Could not open socket

I’ve taken a look into DekoBoko plugin file and I found out that it is using wp_mail() function to send the email instead of ordinary php mail(). I’ve also tried replacing wp_mail() with mail() but I get the same error.

I am trying to send emails through this form to [email protected] email account which is on my VPS and is fully functional so there’s no problem.

I’m using WordPress 2.5.1.

Here is the contact form: https://seowebtips.com/contact/

Please take a look at it and please suggest me what might be a problem.