I think I asked you this already but are you sure that LDAP server is installed correctly ?
I mean it always works but you still need to turn it on and set it up in SA /Open Directory
LDAP settings look fine to me. Can you show us your mail tabs like you did with Open Directories ? I would like to compare your settings to mine. I think then we should be able to sort it out.
Please check your router and enable a STATIC NAT connection to your server's IP address . Let me know if that worked. Then try to connect & receive mail.
Check your Firewall settings.