Operate all kind of settings when connect SMTP with the mail relay source server. You can set the number of simultaneous connections, reception interval, reception size and connection IP.

　　Note

　　　For Business / Enterprise / OEM plans, the number of registered allowed
　　　receiving networks is limited based on your contract. Please be aware that
　　　while it is possible to register beyond this limit, our sales team will contact
　　　you later to discuss the contract details.

Setting the relay server

1.Login to management console and click the server composition tab.

2.Click the server composition on the server configuration list.

3.Server settings dialog will be displayed.

4.Click the relay server settings menu.

5.Following items will be displayed

6.Settings will be saved in management console when clicking the save button.

About "SMTP authentication"

Using "SMTP AUTH," it is possible to record and reference connection logs for each API user in the "Operation Log" menu on Customers Mail Cloud by performing SMTP authentication for each API user.
When you select the "SMTP Authentication" checkbox, the server returns the AUTH extension in response to the client's EHLO command.

About "Authentication Method"

Authentication Method” allows you to change the relationship between ‘SMTP Authentication’ and ‘Acceptable network’ settings.

The options for “Authentication Method” are as follows

• Allow connections using either permitted networks or SMTP authentication
  Authenticate connections using either the allow Acceptable network or SMTP authentication (OR condition).
  SMTP relay is allowed if either of the following conditions is met: the connection is from an IP address configured for the Acceptable network or SMTP authentication is successful.

• Allow connections using permitted networks and optionally use SMTP authentication
  Authenticate first with the Acceptable network, followed by SMTP authentication if SMTP authentication has been properly configured.
  If SMTP authentication is not specified or SMTP authentication fails, SMTP relay will still run as long as the Acceptable network is authenticated.*1
  (If “Avoid connection from other than acceptable network when SMTP-AUTH is used.” was set to “Avoid” prior to 9/26/2024, this option will be selected.)

• Allow connections using both permitted netrowks and SMTP authentication
  If the connection is from an IP address configured for the Acceptable network and SMTP authentication is successful, the SMTP relay will be allowed,

When "SMTP AUTH" is not used, only connections from IP addresses set to the allowed network will be accepted.

If neither “SMTP Authentication” nor “Acceptable Network” is set, mail cannot be sent.

　　*1　SMTP Authentication When Configured to "Allow connections using
　　permitted networks and optionally use SMTP authentication"

　　・SMTP authentication (AUTH) is performed by the SMTP client, not by
　　CMC. CMC notifies the client that AUTH is available.
　　・Use of AUTH is not required. When using IP address-based
　　authentication, the client does not need to execute AUTH.
　　・If the client executes the AUTH command and the ID or password is
　　incorrect, an authentication error “535 error: authentication failed” is
　　returned.
　　The result of the AUTH operation depends solely on whether the
　　authentication credentials (ID/password) are correct.
　　The client's IP address has no effect. Furthermore, it is possible to continue
　　sending emails even after an authentication error is returned.

Receive flow control

You can control the flow of mail received by the mail server using the maximum number of connections and the reception interval. Customers Mail Cloud causes an SMTP transaction to wait until the millisecond specified in the receive interval is reached after receiving one mail.

The received flow rate is calculated by the following formula.

[Email flow rate per hour] = (3,600,000 ms / [Reception interval ms]) [Number of sessions] [Number of MTA]

The number of sessions = 30 and the reception interval = 360 are defalult values, they can be changed.

Reception performance can be scaled out by assigning multiple IPs.

The number of sessions=30 and the reception interval = 360.

The number of IPs is automatically adjusted to handle mail traffic properly.

　　Note

　　　For example, if you want to limit the mail flow to 100,000 mails/hour, specify
　　　the maximum number of connections=10, and the reception interval=360.
　　　With this setting, the set value of mail flow will occur when the mail relay
　　　source server connects 10 SMTP sessions in parallel and sends mail
　　　continuously. If the number of parallel mail relay source servers is 5,
　　　the maximum number of connections=5 and the reception interval=180.

　　Warning

　　　For emails with large content such as attachments, the SMTP transaction
　　　may not end within the reception interval. In this case, the calculated mail flow
　　　rate does not come out. If you want to increase the flow rate of mail per hour,
　　　instead of setting the reception interval extremely short,
　　　Increase the number of sessions (=increase the degree of parallelism).

Reception size control

The content size of the mail received from the mail relay source server has the following restrictions to protect the memory resources of the mail server.

Maximum settable reception size = 786,432KB (768MB) / Number of sessions

　　Note

　　　If the reception size is 20,480KB (20MB), the maximum number of sessions
　　　that can be set is 38.

In the Standard plan, the reception size is set to 20,480KB (20MB).

Saving the settings

The settings will be saved when the Save button is clicked or when the screen transitions to another setting screen (menu click, next button click, etc.) are saved.

Reflection the settings

This will be enabled when the saved settings reflected in mail server.After saving all the settings including other settings in the management console please do reflect settings in the mail server.