Email Service

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1 Introduction

The Email Service app service enables including an email component in your Mendix application. Just add the minimum required configuration and you are good to go.

The app service works with Mendix SSO, so no additional authentication changes are required.

1.1 Typical Use Cases

  • The app service supports sending HTML and plain text messages
  • You can add recipients in the “To”, “CC”, and “BCC” lists to send emails to multiple recipients
  • You can send emails with or without attachments

1.2 Features

This app service enables doing the following:

  • Send HTML and plain text messages to multiple recipients
  • Send attachment(s) with a message
  • Supports setting up a custom Mail From domain to improve your deliverability

1.3 Limitations

  • The total number of recipients in the “To”, “CC”, and “BCC” lists cannot exceed 50
  • The cumulative size of the attachment(s) cannot exceed 10 MB
  • Certain files, for example, executables, scripts, and macros, are not supported as attachments. For an exhaustive list of unsupported file types, see Unsupported File Types for Attachments

1.4 Prerequisites

This app service can only be used with Studio Pro 9 versions starting with 9.4.

2 Installation

  1. Go to the Marketplace and download the SendEmailModule.mpk file for the Email Service.

  2. To add the Email Service to your app in Mendix Studio Pro, follow these steps:

    1. In the App Explorer, right-click the app, click Import module package, and then select SendEmailModule.mpk.


      In the Import Module dialog box, Add as a new module is the default option when the module is being downloaded for the first time, which means that new entities will be created in your app.

    2. In the Import Module dialog box, click Import.

    3. Wait until a pop-up window states that the module was successfully imported. Click OK.

    4. Open the App Explorer to view the SendEmailModule module.

Once imported, the app service is visible in the App Explorer and in the Communication Services category in the Toolbox.

3 Configuration

Email Service is a premium Mendix product that is subject to a purchase and subscription fee. To successfully deploy an app that uses Email Service, you need to get a valid combination of userName and secretKey and configure them as environment variables in the deployment setting.

3.1 Subscribing to Get SecretKey and UserName

  1. On the Email Service page, click Subscribe to order a subscription.

  2. Fill in the Number of End Users, Technical Contact information (First Name, Last Name, Email Address), billing account information, and other required information, and then place the order. The Technical Contact receives an order confirmation email.

  3. Click the link in the order confirmation email to go to the Marketplace Subscriptions page and log in there. The Subscriptions page gives an overview of all the subscriptions of your organization.

  4. Click Email Service to open the service management dashboard.

  5. Click Create Binding Keys.

  6. Enter a meaningful name for the binding keys. Make sure that the name includes the name of the app which uses Email Service.

  7. Click Create Keys to generate the SecretKey and UserName.

    The system generates SecretKey and UserName and also returns MailFromDomain, SPFRecordValue, and MXRecordValue. For more details on SPF and MX configuration, see the section SPF and MX Records.


  8. Copy the SecretKey and UserName. You will use them later for app deployment.

  9. After the order is created successfully, the Technical Contact also receives an email to confirm the email address. Follow the instructions in the email to confirm the email address. Once this email address is confirmed, this email address is used as the sender’s email address when the app sends an email.

3.2 Configuring userName and secretKey for App Deployment

  1. In the App Explorer, go to SendEmailModule > Configurations. You can see SecretKey and UserName are defined as constants.


  2. Double-click SecretKey and enter the SecretKey that you got.

  3. Click OK to save the settings.

  4. Double-click UserName and enter the UserName that you got.

  5. Click OK to save the settings.

  6. After you finish building the app, click Run to deploy your app to the cloud.

4 Usage

4.1 Sending Messages to Recipients

You can use the Email Service in a microflow to send HTML or plain text messages. The Email Service comes bundled with predefined entities EmailAttr and SendEmailResponse.


You can create a list using the EmailAttr entity to specify the To, CC, BCC recipients. For more information, see Working with Lists in a Microflow.

This representative microflow contains an entity with the required attributes, an action to send an email that internally calls the Java action, and a placeholder to capture the return code of the sending email action.


To configure the Send email activity, double-click the activity and specify the following settings in the Send Email dialog box with expression syntax:


  • Required Fields
    • From name – Defines the sender of the email
    • To – Defines the recipients of the email
    • Subject – Defines the subject of the email
  • Optional Fields
  • Cc – Defines the recipients on the CC list of the email
  • Bcc – Defines the recipients on the BCC list of the email
  • Content type – Defines whether the email is a Text or HTML message
  • Body – Defines the body of the email
  • Attachment – Defines the attachment to the email

After the Send Email activity is configured, once the microflow that uses this activity is triggered, the app asynchronously sends out the message to the recipients.

4.1.1 Generating HTML Body Content

The following microflow shows a possible way to generate HTML content using a template. The template contains fixed text with some placeholders for variables.


The second step creates an HTML file from the template contents after possible variable substitution.


The third step generates a string from this HTML file using the String from file action.


In the last step, you can add the variable for the generated HTML content into the Body field of the Send email activity.

4.2 Sending Message with Attachment(s) to Recipients

This is a representative microflow that sends emails with file attachments. The file attachments should have the file types that are supported.


The Attachment attribute accepts a list of FileDocumentObject. You can either use System.FileDocument or use File Dropper to create a list of FileDocumentObject that will be sent as attachments with the email.


4.2.1 Unsupported File Types for Attachments

The following file types are not supported as attachments:

.ade, .adp, .app, .asp, .bas, .bat, .cer, .chm, .cmd, .com, .cpl, .crt, .csh, .der, .exe, .fxp, .gadget, .hlp, .hta, .inf, .ins, .isp, .its, .js, .jse, .ksh, .lib, .lnk, .mad, .maf, .mag, .mam, .maq, .mar, .mas, .mat, .mau, .mav, .maw, .mda, .mdb, .mde, .mdt, .mdw, .mdz, .msc, .msh, .msh1, .msh2, .mshxml, .msh1xml, .msh2xml, .msi, .msp, .mst, .ops, .pcd, .pif, .plg, .prf, .prg, .reg, .scf, .scr, .sct, .shb, .shs, .sys, .ps1, .ps1xml, .ps2 .ps2xml, .psc1, .psc2, .tmp, .url, .vb, .vbe, .vbs, .vps, .vsmacros, .vss, .vst, .vsw, .vxd, .ws, .wsc, .wsf, .wsh, .xnk

4.3 Checking Statistics Using the Usage Dashboard

The Usage dashboard shows the real-time statistics about the usage of an app service. For the Email Service, perform the following steps to check the number of emails sent and data transfer usage:

  1. Log into the Marketplace.

  2. Go to My Marketplace and click Subscriptions on the left navigation menu. The Subscriptions page gives an overview of all the subscriptions of your organization.

  3. Click Email Service to open the service management dashboard. On the Overview tab, the Usage dashboard shows the following statistics:

    • Current Month – Shows statistics for current month usage
    • Last Month – Shows usage statistics for last month
    • Till date – Shows usage statistics from the start of the subscription date to today

5 Increasing the Deliverability of Your Emails

You can make your emails comply with Domain-based Message Authentication, Reporting and Conformance (DMARC) to increase the deliverability of your emails. This is a protocol that helps mail servers validate whether an incoming email is authorised by the administrators of the sending domain. To comply with DMARC, you can use the Sender Policy Framework (SPF) method.

5.1 Configuring the Mail From Domain

Sender Policy Framework (SPF) is an email authentication method. During the delivery of an email, SPF allows the mail server to check whether an incoming email claiming to come from a specific domain is submitted by an IP address authorized by the administrators of that domain.

To achieve The SPF validation, you must meet these two requirements:

  • The domain in the Mail From address of your email must authorize the sending mail server to send the email via a DNS record
  • The domain in the From address of your email must match the Mail From domain (the From address is used in the email header and shown to the email recipients, while the Mail From address is used by mail servers to return bounce messages and other error notifications. Both addresses are used to indicate the source of an email.)

If you use the default Mail From domain of the Email Service, you can only meet the first requirement. To meet the second requirement, you must use your own Mail From domain.

To configure your custom Mail From domain, you should work with your IT administrators to add the MX and SPF records, which you received during the generation of your keys.

5.2 SPF and MX Records

The SPF record is a list of authorized sending hosts and IP addresses for a domain, which is published in the domain’s DNS records.

A mail exchanger record (MX record) shows which mail server is responsible for accepting email messages on behalf of a domain name. It is a resource record in the DNS.

The SPF record and MX record use the formats shown in the following table:

Name Format Value TXT “v=spf1 ~all” MX 10