Catalyst Mail enables you to send emails from within your Catalyst application to its end-users securely. You can add the email addresses for your organization's various departments, such as the marketing, customer support, or finance, for instance, and send mass communication or transactional emails to the users, depending on your app's business logic.

Catalyst enables you to configure either public domain emails or email addresses of your own domains as the sender email in the Catalyst console. You will need to add and authenticate these email addresses and domains in the console before you send the emails. You can also use an email client of your choice instead of Catalyst's built-in email client, and configure its SMTP settings with Catalyst.

SDK and API documentation

Catalyst provides you with SDK tools and an API to send emails to your application users. You can easily incorporate the developer tools in your application's code after you configure the sender emails and domains with Catalyst. Refer to the SDK and API documentation for details:


Key Features of Catalyst Mail

  • Enables you to configure a sender email address with the click of a few buttons and send emails within minutes
  • Highly scalable and ensures speed, efficiency, and consistency irrespective of the load
  • Allows you to store multiple email addresses for various purposes
  • Enables the use of public domain email addresses directly without configuring their SMTP settings, for the domains that support this functionality
  • Provides you with the flexibility of configuring private domains or your organization's own domains and send emails from them
  • Optimized performance of the built-in email client and reliable email delivery helps boost your business credibility
  • Allows you to use an email client of your choice instead of the built-in client
  • Provides support for various functionalities such as file attachments, CC, and BCC while sending emails through the SDKs or the API

Email Configuration

You can configure the sender email addresses in the Email Configuration section of the Mail component from your console. These email addresses can be from public domain email clients such as Gmail, Apple mail, and Outlook, or hosted in a private domain, such as your organization's or business's domain.

Note: In the case of public domain email addresses, you can simply add and verify the email addresses. If the email address is of a private domain, you must first add the domain and validate it. After the domain is verified and validated, you can add the sender email addresses and verify them.

After an email address is added and verified, you can send emails with it from your Catalyst application by coding the logic using the SDK toolkits, or using the API.


Add a New Email Address

To add a new sender email address for your Catalyst application:

  1. Navigate to Amplify then Mail, in your Catalyst console.
  2. Click Add Email Address in the Email Configuration section.
  3. Enter the name that must be displayed as the sender's name and the sender email address, then click Add Email.
  4. Click Add Email.

The email address is now added in your Catalyst project as a sender. You can find all the email addresses that you have added listed in the Email Configuration page.

After you add an email address, you must verify it before it can be used. The Confirmation Status column displays the verification status for each email address.


Verify an Email Address

To verify an email address that was added:

  1. Click Click to confirm for the email address that you want to confirm.

    This will automatically send an email to the email address containing a confirmation code.
  2. Enter the confirmation code that was sent in the pop-up box shown next to the email address.
  3. Click Confirm.

If you did not receive an email with the confirmation code, click Resend Code in the pop-up box. After the confirmation code has been entered and verified, the confirmation status of your email address will be changed to Verified.

You can now send emails with this sender email address from your Catalyst application.


SMTP Configuration

Catalyst uses Zoho's own email client for sending emails from within Catalyst applications. If you prefer to use another email client instead, you can configure the SMTP settings of that email client in your project.

SMTP (Simple Mail Transfer Protocol) is a standard protocol for electronic mail transmission. It handles the communication between the servers used to send and receive emails. To use another email client in place of Zoho's own client for sending emails, you must configure the client's SMTP server in Catalyst by adding its parameters. After the SMTP server has been configured, the third-party email client will handle the emails that you send from your Catalyst application.

Note: Although you can use public domain email addresses to send emails from Catalyst, Zoho cannot guarantee the functioning of these email domains. Your emails may sometimes not be delivered or be delivered in the receiver's spam folder.

Some public domain email providers, such as Yahoo Mail, cannot be used directly in Catalyst to send emails. In such cases, you will need to configure the email client's SMTP settings with Catalyst to be able to use it. If the public domain email can be used directly with Catalyst, configuring its SMTP settings is optional.

To configure the SMTP server of another email client in Catalyst:

  1. Click the SMTP Configuration tab in the Mail component.
  2. Enter the following SMTP parameters of the email client:
    • Sender Address: The sender email address that you want to configure with the email client.
    • SMTP Server Host: The name of the email client's SMTP server host.
    • SMTP Server Port: The port number of the SMTP's server. The available ports are 25, 465, 587, and 2525.
    • SMTP Account Username: Your SMTP account username.
    • SMTP Account Password: Your SMTP account password.
    • SMTP Account Security Mode: You can use SSL or TLS encryption to make your connection secure by encrypting the communication channel. You can select None for no security.
  3. Click Save.

The SMTP server is now configured in your Catalyst project. You can now send emails from the application, and this external client will handle the process.

You can also disable the email client if you do not require it, using the toggle switch on the top, and re-enable it when needed.



If the sender email addresses you wish to use are not by public email providers such as Gmail or Outlook, and are hosted on a private domain such as your business's own domain through third-party email providers or hosting services, you will need to add and validate that domain in Catalyst. You can add the sender email addresses, after you validate the domain.

Catalyst requires the authenticity of external domains and sub-domains be verified. Domain validation is mandatory, as Catalyst needs to ensure that the domain an email is sent from is valid and trustworthy. Catalyst performs this validation of the domains and sub-domains you add, through their DNS configurations. This is done using the following email authentication and validation standards:

  • DKIM: DKIM (DomainKeys Identified Mail) is an authentication method which uses encryption with public/private keys, to validate whether the emails are generated from the authorized servers.
  • SPF: SPF (Sender Policy Framework) is an email validation system which looks for spoofed or forged emails using a specific SPF record published for the domain with the details of the hosts that are permitted by the domain's administrators.

This enables Catalyst to provide security for the applications you build with it.


Add Your Own Domain

To add an external domain in Catalyst:

  1. Click the Domain tab in the Mail component, then click Add Domain.
  2. Enter the email address of the external domain.
  3. Click Create.

The domain is now added in the project and will be displayed in the Domain section. You can add and use multiple domains for sending emails from your application. You must now verify and authenticate the domain before you use it.


Verify a Domain

To verify an external domain:

  1. Click Verify Code for the domain you want to verify in the Domain section.

    This will automatically send an email to the email address containing a confirmation code.

    If you don't receive the email with the verification code, click Resend Code in the Verify Code box.
  2. Enter the verification code that was sent to the email address in the pop-up box in the console.
  3. Click Confirm.

If the verification code matches, the domain will be displayed as verified.


Authenticate your Domain

You will also need to authenticate the external domain by validating its DKIM and SPF records. To do this, you must configure the DKIM and SPF record codes that are generated in Catalyst with the DNS settings of your domain's host.

To authenticate an external domain:

  1. Click Validate for the domain you wish to authenticate in the Domain section..
  2. Copy the SPF and the DKIM record codes shown in the pop-up window.
  3. Navigate to the DNS settings of the domain's host and paste the SPF and DKIM record codes in the respective fields. This process will vary depending on the domain host you use.
  4. After the record codes have been added and saved in the domain's host, click Authenticate in the Authenticate Domain pop-up in the Catalyst console.

After the SPF and DKIM record codes have been validated by Catalyst, your domain will be displayed as authenticated.

You can now add and verify the email addresses of this domain to send emails from Catalyst in the same manner as described in this section.


Send Emails

You can send emails from your Catalyst application after you configure the sender email address, and optionally the private domain and the SMTP server of the email client. The code templates for Java and Node.js platforms, as well as the API specifications to send emails are mentioned in the respective help pages.

Catalyst enables you to set multiple email addresses as the receivers, and to CC, BCC, and reply to, through a single send mail operation through the SDKs or the API. You can also attach files in the emails you send. The maximum supported limits for email recipients and file attachments in a single send mail operation are specified below:

  • To address: 10
  • CC: 10
  • BCC: 5
  • Reply to: 5
  • Number of file attachments: 5
  • Size of file attachments: 15 MB (through a single file or multiple files upto 5 files)

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