Testing communication » Troubleshooting inbound
Configuring your firewall to accept inbound emails
Inbound email traffic is received on TCP/IP port 25. Therefore, you must allow traffic on this port to reach the machine where Xeams or any SMTP server is running.
How do you know if port 25 is open?
You could run the Quick Test utility
at AboutMyX.com to see if servers outside your network can connect to your SMTP server.