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What Should I Do If Emails Configured on an ECS Cannot Be Sent?

Updated at: Mar 17, 2020 GMT+08:00


  • For the emails sent using the browser:

    When you use a browser to log in to your mailbox, HTTP is used, and the default port number is 80. However, SMTP is used between email servers.

    If you use a browser to send emails, enable port 80 for TCP in the outbound direction.

    1. On the page providing details about the target ECS, find the security group and click the security group ID.
    2. On the Security Group page, click the Outbound tab and then Add Rule.
    3. In the dialog box that is displayed, set Protocol/Application to TCP and Port to 80. Then, click OK.
      Figure 1 Adding port 80
  • For the emails sent and received by an email client:

    If you use an email client, SMTP is used to send emails and the port number is 25; POP3 is used to receive emails and the port number is 110.

    For details, see steps 1 to 3.

    Add an inbound rule with Protocol/Application set to TCP and Port to 110. Add an outbound rule with Protocol/Application set to TCP and Port to 25.

Related Operations (Requesting for Permitting TCP Port 25 for Outbound Transmission)

Before sending the request, you must agree and guarantee that TCP port 25 is only used to connect third-party Simple Mail Transfer Protocol (SMTP) servers and that emails are sent using the third-party SMTP servers. If you use the EIP specified in the service ticket to directly send emails over SMTP, we will permanently disable TCP port 25 for you and will no longer enable it even you request.

  1. On the Create Service Ticket page, choose Products > Elastic Cloud Server.

    For details about how to submit a service ticket, see Submitting a Service Ticket.

  2. Click Open Port 25 under Select Subtype and click Create Service Ticket.
    Figure 2 Creating a service ticket
  3. On the displayed page, enter the required information as prompted.

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