Sending classic transactional email via SMTP

To start sending transactional email with SMTP, you need to point your application to our servers.

SMTP connection details

  • Server —
  • Ports — 587, 25, 465 and 2525 supported, all ports support TLS
  • Username — Any valid SMTP token
  • Password — Same as username

NOTE: SSL is not supported.


To find your SMTP token, open Transactional, then click Send with SMTP in the right sidebar. If you haven't clicked the Enable SMTP button yet, do so, then you will be able to copy or create new tokens from this page.

Message content

There are a few things to consider when sending classic transactional emails:

  • You may send to up to a total of 25 recipients across the To, CC and BCC fields.
  • Both the From and To fields can accept a name in addition to an email address, for example Jane Smith <>.
  • If you’re importing your own HTML email it should include a plain text version. If there is no plain text version with the imported files, one will be automatically generated from your HTML version.

Grouping emails for reports

Though you can send transactional emails without grouping them, it is impossible to track your results and view meaningful reporting this way. To get the most out of functionality and reporting, it is necessary to group related emails together. For example, your "Password reset" emails would be filed under the one group, whereas your "Order confirmation" emails would form another. Emails without a group are filed under "Ungrouped emails" in our reports, and as such won't provide useful feedback.

To create a group with classic transactional email, you can create a group name by passing the following as a header:

X-Cmail-GroupName: XXXXXX

Where XXXXXX is the name you want for the group.

NOTE: We support SMTP group headers from Mailgun, Mailjet, Mandrill, Postmark and Sendgrid, making the switch easy and enabling reports without having to redeploy code. If your existing transactional provider allows for multiple group names, we take the first provided.

Advanced HTML email header options

By default all HTML messages are tracked for opens and clicks, and we move CSS inline for better email client support. However, you may turn off these options by passing the appropriate header as false instead of true:

  • X-Cmail-TrackOpens: true
    Whether to insert a tracking beacon.
  • X-Cmail-TrackClicks: true
    Whether to rewrite links into trackable links.
  • X-Cmail-InlineCSS: true
    Whether or not to bring CSS inline.