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Helo gives you full visibility into every email you send. From the moment a message is accepted to the moment it’s delivered, opened, or bounced, every event is captured and queryable — in real time. Activity comes in two forms:
  • Events — an ordered log of every delivery lifecycle event for every message
  • Messages — a view of each distinct message along with its full delivery history

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Events

Every message goes through a series of lifecycle events as it moves through Helo’s infrastructure.

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Querying events

You can retrieve events via the API with a wide range of filters:Results are paginated using a cursor. Pass the after value from a response to fetch the next page. Each page returns up to 500 events.

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Messages

The messages view gives you a higher-level perspective — one record per distinct message sent, each with a summary of its delivery status and recipient list. Each message has:
  • A unique messageId
  • The channelId it was sent through
  • mailType (transactional or broadcast)
  • mailSource (api or smtp)
  • deliveryType (live or sandbox)
  • status (queued or sent)
  • Subject, recipients, and tags

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Message details

Fetching a single message by ID returns the full picture:
  • Headers — from, to, cc, bcc, reply-to addresses
  • Content — plain text body, HTML body
  • Attachments — filename, disposition (inline or attachment), and size
  • Tracking settings — whether open tracking and link tracking were enabled
  • Events — the complete ordered history of events for that message

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Querying messages

Messages support the same filters as events: channelId, startDate/endDate, recipient, subject, tags, mailType, and status. Results are paginated up to 100 per page.

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Statistics

Helo aggregates your sending data into statistics so you can understand trends and monitor the health of your sending over time. Stats are always broken down by mail type — transactional and broadcast — so you can see how each sending stream is performing independently. The following metrics are tracked:

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Time-based aggregations

Stats are available at three granularities:
  • Hourly — one data point per hour, for a given from/to range
  • Daily — one data point per day, for a given from/to range (pass a timezone to align days to your local time)
  • Totals — a single aggregated summary for the entire from/to range
All three endpoints support filtering by channelId and by tags.