The campaign's History tab is going to be your greatest asset for tracking the status of individual mailers, testing integrations, and viewing incoming Request Details. Once a One Time Send has launched and processed or a trigger is set live and sending requests, a list of individual mailers will start to appear.

Mailing States & Environment

In the top right you'll see a tool for filtering by Mailing State and/or Environment, the option to Download a CSV record, and a calendar tool for filtering by date. In the top left you'll see a mailing count which reflects the filter settings.




Confirming all details of the mailing and production.


The mailer has passed data and suppression checks and is in print production.


Not mailed as part of the control group.


The mailer recipient was found on your Do Not Mail list, or suppressed due to another setting such as regional, domain, or recently mailed.


Scanned and processed for delivery by USPS.


The mailer has received one or more USPS mail scans and is on its way to the recipient. The Mailed state also falls under in-transit.


An exception occurred while processing. This includes invalid addresses, unmatched emails for Address Enrichment, campaign budget exceeded, or insufficient account credit.


Incoming trigger requests using your Production API Key.


Incoming trigger requests using your Test API Key.

Numbers and mailing status are most accurately reflected under the History tab. While the graphs shown on the overview page are a useful visual aid, always refer to the campaign History for the most detailed account.

Once a mailer is In Transit or Mailed, status updates are based on incoming scans from USPS. If you notice a slight lag in delivery updates, we recommend checking back in later or the following day in case USPS hasn't updated their data yet.

Download CSV

The Mailing State, Environment and Calendar filter setting will be applied when downloading a CSV record. Shortly after clicking Download CSV, you'll receive an email from no-reply@heypoplar.com with a download link - this email can take up to 15 minutes to arrive depending on the amount of data requested. Your CSV record will contain the following data columns:

Column Name



The ID of the parent campaign.


The name of the parent campaign.


The ID of the individual mailing.


The current state of the mailing.


The timestamp when the mailing was created. This is in UTC.


The scheduled mailing time (if set).


The type of postage applied to the mailing (usually either first class or standard mail).


The format of the mailing (e.g. "6x9 postcard")


The ID of the creative used for the mailing. If you are running an A/B test of multiple creative then this will be different per creative.


The name of the creative used for the mailing.


The email address submitted with the mailing.


The external_id provided when creating the mailing.


The name printed on the mailing.


Address line 1.

When using the address append functionality, as per our terms of use, this information is redacted and not provided for download.


Address line 2.

When using the address append functionality, as per our terms of use, this information is redacted and not provided for download.






The expected delivery date of the mailing.

This is an estimate calculated based on submission time and historical mailing data.


The date of the USPS delivery scan. Typically this occurs at the local post office, within 0-48 hours of the mailing arriving at the recipients mailbox.


The estimated cost of the send based on the postage and format of the mailing.


The type of send. Valid values are API and MANUAL. This indicates if the mailing was triggered by our API or if it was created as a one-time send.


This allows you to group mailings that are part of a one-time send.


The merge tags used for the mailing.


This indicates if a test API key was used for the mailing. Valid values are test and production.

Individual Mailers

Click into a mailer to see a summary of the Mailing Details, Event Log, and Request Details. If the mailer is or was in print production, you'll see an image preview with address and merge tag (if applicable) data applied and the option to download a PDF proof.

Mailing Details

Under the Mailing Details you see the Recipient Address, Campaign name, Creative name, Postage Type, Trigger Source (API Request or Manual Send), Creative Type, send_at trigger setting, Estimated Cost (price per piece), and a list of any custom merge tags used showing their name and value as populated based on mailing data.

Event Log

The Event Log shows a Timestamped record of how long the mailer spent in each step of the mail cycle from "Created" to "Delivered."

Request Details

If the mailer was launched via trigger or integration with our Mailing API, the individual webhook data will be shown in the Request Details. The webhook should match the sample API Request from the Data Guide at the bottom of the creative's page.

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