[toaster] strange delay on smtp connections

[Jose]

Hi...I'm experiencing a problem with my smtp server: a long delay when users 
connects to it:

[EMAIL PROTECTED] root]# telnet localhost 25
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
-----------------------------------> 30 - 120 seconds delay
220 domain.com ESMTP

What can cause this delay ?:(
I'm using smtp-auth, no rblsmtpd, no clamav, no simscan, no spamassassin...

Thanks in advance for any help