Now my activation email not working again..

[souluna]

SMF Version: SMF 1.0.5
Hi all..

I want to ask one question about activation email. I have use smf forum for 4 month and working good.
But now all of my new member not retrieve the activation email..

And i have tested with new account with my email, and i get same problem. I try to resend activation email but i get this message

An Error Has Occurred!
A new activation email has successfully been sent.

How can i solve this problem?
My forum is hxxp:www.souluna.com/forum/index.php [nonactive]

[BB]

The same happens to me.. 
Any help, please?