Testing Mail Servers

Testing Mail Servers

Testing Mail Servers

  • Use MX Toolbox SMTP Diagnostics to test if an email server is running
  • This test will do the following:
    • Connects to the designated mail server via SMTP
    • Determines whether the mail server is an open relay
    • Verifies whether the mail server has a reverse DNS (PTR) record
    • Verifies whether the mail server supports Transport Layer Security (TLS) 
      • TLS is the successor to Secure Sockets Layer (SSL)
      • The TLS and SSL protocols enable secure communications over the Internet
    • Evaluates the connection time and transaction time of the mail server
  • If you don't know the address of the mail server, begin with an MX Lookup

Troubleshooting Incoming Mail Issues

  • Verify your recipient policies are configured correctly
  • Verify your mail server is configured to accept Internet mail on TCP port 25 from anonymous connections
  • Verify your firewall has an incoming rule that accepts connections from TCP port 25
  • Verify a mail exchange (MX) record exists for your domain on an Internet DNS server
  • Verify the MX record points to the externally facing Internet domain of your mail server
  • Verify your mail server is accessible to remote mail servers on the Internet

Troubleshooting Outgoing Mail Issues

  • Verify your mail server that sends Internet mail is configured to use TCP port 25
  • Verify at least one connector contains an address space of * for all external domains when you are using SMTP connectors
  • Verify your mail server's DNS settings are correct and that it is able to resolve external DNS names

Installing Telnet on a Windows Machine

  • Use Add/Remove Programs in the Control Panel to install Telnet
Add and Remove Features Window

Using Telnet to Test SMTP Communication

  • Open a command prompt and type "telnet /?" to view the telnet options
  • Type "telnet" at the command prompt and press <Enter>
  • Type "SET LOCALECHO" at the Telnet prompt to view the responses to the commands
  • Type "o <your mail server domain> 25, and then press ENTER
  • If Telnet is unable to make a connection, type "netstat -an |find /i "listening"" at a regular command prompt on the mail server to see if it is listening on port 25
  • You may need to point to the private IP address of the server instead of the localhost ( when the mail server is on the same machine as the Sitecore site