The following ports are blocked for outbound traffic with all dynamic IP addresses.
- 25 - SMTP
- 137 - NetBIOS Name Service
- 138 - NetBIOS Datagram Service
- 139 - NetBIOS Session Service
- 445 - Microsoft Directory Service (Windows file sharing, SMB/Samba)
For more informaiton on ports and associated services please see the following Wikipedia entry.
https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers