mail server work with or no rDNS/PTR ?!?

Hi,
 
I have a big problem with mail server and can not solve it....
 
The problem is that when I tick the
rDNS Check (recommended): [ ] Drop all emails if no rDNS/PTR

I do not get some letters and also I can not send via SMTP port 25  ....

I can not send a message even to myself..
 
When I checked out
rDNS Check (recommended): [ ] Drop all emails if no rDNS/PTR

I can get and send via SMTP and across all possible ports 25, 465 ...
 
rDNS/PTR = hosting.myname.com SUCCESS [Check SenderBase] - it's OK
 
What could be the problem?

 
Thanks in advance!
 BR
Venty