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Troubleshooting SMTP Issues


Basic Configuration for SMTP Server


Description: User was unable to configure the SMTP e-mail server.


  1. Check the SMTP server settings.
    • SMTP server address—Check the host name or network address of the SMTP e-mail server. Typical SMTP server addresses or host names are as follows:




      • AWS

    • TLS—Check whether Transport Layer Security (TLS) option is enabled. This setting ensures that the information is transmitted over an encrypted channel. Not all SMTP servers support encryption. If TLS option is enabled for an SMTP server that does not support TLS, then disable the TLS option.

    • Port—Check with your e-mail service provider for the port number that the SMTP server listens to. Generally, port number 587 is used for a TLS connection and port number 25 is used for unencrypted connections.

    Typical SMTP server settings are as follows:

    •—Set TLS to No and port number to 25

    •—Set TLS to Yes and port number to 587

    •—Set TLS to Yes and port number to 465 or 587

  2. Check the SMTP authentication settings.
    • Check whether the e-mail server requires authentication. If yes, then specify the following options.

      • From Name

      • User Name

      • Password

      • From E-mail Address


      If Gmail blocks SMTP e-mails, then log in to Gmail account, navigate to Advanced Settings > Security > Less secure app access and click the toggle button to turn on Allow less secure apps option.

  3. Test SMTP settings by sending a test e-mail.

    If you are unable to send a test e-mail:

    1. Check the SMTP server settings to see if they match the SMTP server provider’s settings.
    2. Check authentication credentials.
    3. Check the SMTP server provider’s security settings for SMTP (for example: Gmail blocks SMTP email unless user selects less secure app settings on their gmail account).
    4. Check whether there is network access from CSO to the SMTP server.
    5. Check whether the firewall is blocking SMTP traffic to SMTP server or whether the ports are blocked. If the server settings and authentication settings are correct, check whether the firewall is blocking port 587 and 465 and SMTP traffic. If it is a case of the firewall blocking, then work with the network administrator to unblock ports 465, 587, and SMTP traffic.

Basic Configuration for AWS CSO Installations


Description: User was unable to send e-mail from Amazon Web Services (AWS) CSO installations.


AWS uses Amazon Simple Email Service (Amazon SES), which is a cloud-based e-mail service. In case of AWS installations, in addition to configuring SMTP server settings, the users must be registered with the AWS SES.

  1. Register AWS SMTP email servers. Navigate to and understand the following topics:
    • Sending Email

    • Receiving Email

    • Controlling Access

  2. Configure CSO SMTP Server settings. The information from the AWS SMTP e-mail setup must be added to CSO SMTP Server settings.

    The SMTP server settings are:

    • Server address—

    • TLS—Enabled

    • Port Number—587

  3. Configure SMTP authentication settings such as user name, password, and e-mail address. A sample format for e-mail address is: .
  4. Register the users to the AWS SES. The network operator who configure the AWS SES must request the users to join the AWS SES.

    The user receives an e-mail as follows:


    For brevity, only a part of the e-mail output is listed. Rest of the e-mail content has been replaced with ellipses (...).

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