Mail Agents

Mail Agent is used to group or categorize your Transactional emails at a high level. Eg., Mail Agent 1 will be used for sending OTP emails and Mail Agent 2 for invoice emails. You can set up multiple domains under the same Mail Agent. This is done to group all the transactional emails sent using these domains. The email activity (opens, clicks, and bounces) for all the emails sent via the grouped domains can be tracked in the Processed Emails section in your Mail Agent. Within a Mail Agent, you can configure webhooks (for Opens, Clicks and bounce), enable tracking (open tracking, and click tracking), and upload and manage files that are added as inline images or attachments to your emails. 


You can create a maximum of 50 Mail Agents for your ZeptoMail account.

Create a Mail Agent

You might have created a Mail Agent during the on-boarding process. To create and use additional Mail Agents, follow the instructions below:

  1. Log in to ZeptoMail application
  2. Select 'Mail Agents' from the left panel
  3. In the Mail Agents section, you can view the Mail Agents list. 
  4. Click 'Add Agent' from the top bar to create a new Mail Agent.  
  5. Provide the Mail Agent NameDomain, and Description for the new Mail Agent. While creating your Mail Agent, you can associate an existing domain or add a new one.
  6.  If you add a new domain, it will be automatically listed in the Domains tab located in the left panel.Click on +New domain in the drop-down to add a new domain.
    Create a Mail Agent
  7. Click Add to create the new Mail Agent.

Sections of a Mail Agent

You can associate more than one domain to each Mail Agent. If you want to configure ZeptoMail service for multiple applications, then you can create separate Mail Agents for each application. Eg., Mail Agent 1 will be used to send application 1 emails and Mail Agent 2 will be used to send application 2 emails.

From the list of Mail Agents, select any Mail Agent to view the related details. The details related to the Mail Agent are grouped under different tabs:

  • Overview - A summary of the number of Transactions using the Mail Agent. 
  • Domains - Details of the domains that are linked with the particular Mail Agent.
  • Processed Emails - Logs of the emails that were processed using the Mail Agent.
  • Webhooks - To trigger HTTP call back to the application, based on configured events, in a Mail Agent. 
  • Email Tracking - To track the email activity - email open and click actions for the emails.  
  • File Cache - To upload any inline images, attachments that need to be sent in the email. 


You can get an Overview of the Mail Agent (for the last 15 days) in terms of the number of emails, the number of bounces, opened count, and so on. This can be based on different chunks of time periods, chosen by you. 

The number of emails sent vs count of emails opened/ clicked along with the count of hard/ soft bounces is plotted in a chart to provide you an easy overview at a glance. 


You have to enable Email Tracking to track the number of opens and clicks.

Setup Info :

Transactional emails are generated by your application. You need to configure the application with the MailAgent in ZeptoMail to trigger emails from the application. There are two ways in which your emails will be sent - SMTP and API.

Navigate to the Setup Info tab to access these two methods. 

  • API Method : To connect to ZeptoMail via API method, use the Send Mail Token in the authorization header of your API request body. Copy the unique Send Mail Token generated for your account and add it to your API code.
  • SMTP Method : To connect to ZeptoMail via SMTP method, add the following details :

    • Server name :
    • Port number and Authentication : 465(SSL), 587(TLS)
    • Username : email apikey (We also support applications that use the From address as the username)
    • Password : Visit here to check your password.
  • Wordpress plugin for ZeptoMail :

    If you are a WordPress website owner, you can connect your website to ZeptoMail using our plugin. You can get the plugin setup details from the WordPress tab. Click here to know more about the setup process. 

    Copy and use Send Mail Token to connect your application with this Mail Agent.
  • While sending your email via SMTP, the bounce address added in your Mail Agent should be used. If you leave the bounce address field empty or configure it with an invalid bounce address, then ZeptoMail will use its default bounce address while processing your email.
  • If your SMTP application is restricting longer passwords, then you can generate a shorter password. Shorter passwords are generally less secure. Click on Generate new token to get your shorter password.
  • When you generate a shorter password, your application can either use the From address as username value or you can generate the new Username value for the shorter password by clicking on username value.


In this section, you can associate your domains to the Mail agents. Multiple domains can be added to a Mail Agent. All the emails sent using the associated domains are grouped under this Mail Agent. In this section you can: 

  • Associate or dissociate a domain
  • View the list of domains associated with your Mail Agent
  • View the verification status of the associated domains
  • View the SPF, DKIM, and the CNAME values for your associated domains
  • Setup bounce address(es) for your associated domains that are verified (SPF, DKIM, and CNAME)

You can add 100 domains in your account. The Domains page will provide you in-depth information about domains along with detailed instructions to verify domains, edit a domain or delete a domain.  

Processed Emails

You can view the detailed log of all the emails processed by the Mail Agent in this section. The logs will be based on the processed time of the email. Select any email to view the status of the particular email. You can also use 'Search' to find the status of specific emails. 


The Processed Emails page has detailed instructions on using various parameters and also about the various delivery status associated with the email. 


In most simple terms, Webhooks are user-defined HTTP callbacks that are triggered by an event. In ZeptoMail, Webhooks can be used to relay data based on recipient activity on the sent emails, to your application. The events for which the recipient data is relayed by the webhook are Opens, Clicks, and Bounces of the email. A Webhook instantly relays data to the configured URL and your application is instantly notified. 

When the specific event occurs, the Webhook is triggered. That is, an HTTP POST request is made to the URL (or URI) configured by the developer to receive the webhook. The most useful feature of email webhooks is getting the user details when any or all of these events occur. The Webhook URL has to be configured in ZeptoMail by the application developer to receive recipient details when these events occur. You can preview your webhook data within a Mail Agent and test it.  

ZeptoMail supports various types of Webhooks for different purposes. Refer here to learn about Webhooks and its supported types.

Email Tracking

When you send Transactional emails, tracking the email to understand user behaviour becomes very vital for the application. Since Transactional emails are very critical, open and click-tracking provides information on how the users respond to your emails.

In some cases, you might need to know whether the email delivered to your user was opened or not. Email Tracking helps you to track the click and open status of the emails sent via ZeptoMail. 

This page provides you detailed information on Tracking and instructions to configure Tracking in ZeptoMail.  

File Cache

When you send emails, you might need inline images or attachments that need to be sent with the email. Those commonly used attachments can be uploaded to File Cache. Each file (image or attachment) you upload to ZeptoMail will have a unique FileCacheKey generated by the system. You need to use this FileCacheKey to link them to the Transactional emails sent by you. The total email size, including the attachments and inline images should not exceed 15 MB in size.  

Refer File Cache section for detailed instructions for uploading and including inline Images/ Attachments to the emails. 

Delete a Mail Agent

You can delete the Mail Agents that you no longer use. Only Postmaster has permission to perform the deletion operation. Before deleting the Mail Agent, you have to initiate the Mail Agent shut down process. The shutdown period is for 45 days and your Mail Agent data will not be deleted during this period. After 45 days, ZeptoMail will automatically delete the Mail Agent and its information.

Here are a list of things to keep in mind before initiating the Mail Agent shutdown process:

  • Once the shutdown of a Mail Agent is initiated, the process and the associated actions cannot be reverted.
  • After the initiation of the shutdown, emails cannot be sent using HTTP or SMTP from the Mail Agent.
  • All actions performed by the Mail Agent such as scheduled emails, tracking, webhooks, triggering, etc., will be blocked immediately after the shutdown is initiated.
  • After Shutdown, information such as processed email logs, and reports will remain till the deletion of the Mail Agent. 
  • After the deletion of the Mail Agent, all information corresponding to the Mail Agent except the associated domains will be deleted irreversibly.

Steps to initiate the shutdown process:

  1. Log in to ZeptoMail application
  2. Launch Mail Agents section from the left panel. 
  3. Select the Mail Agent you want to delete.
  4. On top right corner click on the power icon to Shut down the Mail Agent.

  1. In the Shutdown Initiation popup, provide your account password, agree to proceed and click on Shutdown.

The Mail Agent will be permanently deleted after the completion of 45 days from the shutdown initiation period. 

Points to remember

  • You can add and use up to 100 domains in your ZeptoMail account.
  • All the domains you add can be associated to a single Mail Agent or multiple Mail Agents.
  • The domain should be verified, to use it in the Mail Agent for sending Transactional emails. 
  • You need to configure a bounce email address with the verified domain in the Mail Agent
  • You can use different domains, for sending different types of Transactional emails from the same MailAgent. This is purely based on your sending requirements. 
    • Example: The company Zylker sends two types of transactional emails - Daily reports and account alerts from the same Mail Agent. It uses the sub-domain for daily reports and for account alerts. Both these verified sub-domains are part of the same Mail Agent.
  • However, you can also send different emails using different Mail Agents. For instance, Zylker can use Mail Agent 1 to send welcome emails and Mail Agent 2 to send daily reports. Mail Agent 1 will have the sub-domain added to it. Mail Agent 2 will have sub-domain added to it.
  • The maximum number of recipients you can add in your email (which includes to, cc and bcc fields) is 70.
  • The maximum size of the email you can send including the headers, in-line images, and attachments is 15MB.
  • ZeptoMail does not support certain formats of in-line images and attachments. Click here to view the list of unsupported formats.


Before you get started it is important to know that ZeptoMail is for sending transactional emails like welcome emailers, password resets emails, OTPs. We do not support sending of bulk emails or promotional emails like newsletters or marketing campaign emails. If you are looking for a bulk email provider, check out Zoho Campaigns.