Skip to content

Receiving server

Perform settings to receive mails such as Inbound Webhook or emails received using email forwarding (inbound emails) or If e-mail (bounce e-mail) returned from the destination server when e-mail delivery fails.

In Standard plan, you can only set the allowed domains for Inbound.

Setting the receiving server

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

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

  3. Server settings dialog will be displayed.

  4. Click the receiving server settings menu.

    receiving server settings

  5. Following items will be displayed.

    Item Required Description
    Port Yes Bounce mail and inbound mail are forwarded from port 25 to port 10026 and received. This value cannot be changed.
    Max sessions Yes Input the maximum number of simultaneous SMTP session connections that can be accepted. Specify in the range of 1-100.
    Receiving interval Yes Input the interval (processing time per mail) for receiving mail from the mail relay source server in milliseconds. Specify in the range of 10-10000.
    Receiving size limit Yes Input the content size of the received email in KByte units.
    Acceptable domain No Input the domains that you want to allow email reception. See below for details.
  6. Settings will be saved in management console when clicking the save button.

  7. In the receiving server settings as well as the relay server settings, Receive flow control, Receive size control can be performed.

about condigions for judgement of spam mail regarding permitted domains for receiving

In the following cases, the email will be judged as spam mail and rejected.

  1. If the header from is a permitted domain of the receiving server

    Even though the email is supposed to be received from an external source, it is judged to be suspicious because the from field is in thename of the recipient's own domain.

  2. If the header from and to are the same email address

    This is also judged as suspicious email addressed to you.

Receiving the bounce

Perform settings to receive bounce emails.

Initial settings is registered in the reception permission domain, and in Advanced Settings -> Envelope From domain, you can perform the rewriting settings to


If you want to return the bounce mail to the envelope From set by the mail relay source server, change the envelope From to the "Do not rewrite" setting.

Rewrite the domain of the envelope From to the following, and Customers Mail Cloud will receive the bounce mail.

Server configuration Domain

Using your own domain

Describes how to use your own domain for the envelope From.

STEP1 : Designing your own domain

In order for Customers Mail Cloud to receive bounce emails, designing the domain used for the envelope From is required.

For example, both the header From and the envelope From use and is the domain that operates your organization's email address. In such cases,because It is necessary to separate the reception of normal mail and bounce mail, the envelope From must be assigned a subdomain of the header From.

Before Change
Item Mail address
header From
envelope From without settings (uses
After Change
Item Mail address
Header From
Envelope From

STEP2 : Setting the MX record

Register the receiving server in the MX record of the domain that operates the envelope From. (This operation is done on the DNS server that manages your own domain)

Server configuration name Receiving server
Server configuration name Receiving server

STEP3: Setting the SPF record

Specifies the SPF record provided by Customers Mail Cloud for the domain that operates the envelope From. For more about SPF record please refer to Registering the SPF.

STEP4 : Setting your own domain

There are two ways to set your own domain to the envelope From.

Sender Domain Settings

When it is necessary to set the domain of the envelope from for each header from, such as when operating DMARC, perform the 'envelope from' settings from sender domain settings.

Advanced Settings

To rewrite the envelope from of all emails sent via Customers Mail Cloud at once , operate the 'envelope from' settings from "Advanced Settings".


Rewriting the envelope from set in "Sender domain settings" has priority over the settings in "Advanced settings".

STEP5 : Receiving the bounce

  1. Click the "Receive Server Settings" -> Bounce tab of the allowed domains.

  2. Input the envelope from domain of ( in this example).

Domains set to envelope from will automatically receive bounces.

Receiving inbound

For using Webhook and mail forwarding performs settings to receive mails.

This section describes the settings to receive by mail forwarding and Inbound Webhook of Customers Mail Cloud (emails sent by email sending applications such as email forms).

STEP1 : Design of destination email address

Customers Mail Cloud decides the recipient email address for it to accept email.

Item Mail address
destination email address

STEP2 : MX record settings

Register the following SMTP host in the MX record at which assigned as the domain of the destination email address to receive emails with Customers Mail Cloud. (This operation is done on the DNS server that manages

Server configuration name SMTP host
Server configuration name SMTP host

STEP3 : Receiving permission domain settings

Click the "Receiving Server Settings" -> "Inbound" tab of the allowed domain. Input the domain of the destination email address ( in this example).

STEP4 : Webhook Settings

When using an inbound webhook, register the notification conditions for the webhook.

Click "MENU" -> "API Settings" at the top right of the management console screen, Click the "Webhook" tab -> "Inbound" tab.

Set the following in the notification conditions.

Items Value
Header name Input 'To'
Header value Input a regex for the destination address that handles the Inbound Webhook .(info@mailform\.example\.com in this example)

STEP5 : Mail forwarding settings

When using mail forwarding, register the forwarding conditions of the receiving server of mail forwarding.

Please refer to the receiving server of "Mail forwarding" -> "Add filter".

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.

Reflecting 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.