API Calls

API Calls are used to meter usage of the Mailsac service. API Call usage resets on the first of the month UTC.

What Counts as an API Call?

The following actions count as an API call:

The following actions do not count as an API call:

  • Viewing messages via the Website
  • Deleting messages via the website
  • Forwarding Mail to another Mailsac address

Monitor API Usage

API usage can be monitored via API Usage. The API Usage page includes current month, past usage by month, and all time API calls.

API Usage is not updated in real time. The metrics are calculated periodically throughout the day.

Calculating API Usage

API calls can be calculated by summing the number of calls to the REST API, messages published to WebSockets, Webhooks, and Slack, and messages sent to a private domain.

Inbound Message API Calls

Inbound messages are tracked as an API call. The first forward of the message to Slack, Webhook, or WebSocket does not count as an additional API call. Second and third forwards will count as additional API calls.

Public Domain API Calls

Validated Custom Domains can be set as public. API calls to the domain, its addresses or messages will be tracked on the domain owners account.

Example API Calculation - Fetch Messages and Body of an Email

Viewing the body of a message via the REST API requires 2 API calls.

  1. The first call is used to list all the messages in the inbox.
  2. The second call is used to retrieve the plaintext body of a specific message.

Example API Calculation - Forward Message from Private Domain to Slack

Receiving a message and publishing to Slack requires 1 API calls.

  1. The first call is to receive the message in a private domain.

The first forward of an inbound message to Slack, Webhook, or WebSocket does not count as an additional API call.

Example API Calculation - Forward Message from Private Domain to Multiple Destinations

Receiving a message and publishing to Slack and a WebSocket requires 2 API calls.

  1. The first call is to receive the message in a private domain.
  2. The second call is for the second message forward.

The first forward of an inbound message to Slack, Webhook, or WebSocket does not count as an additional API call.

Example API Calculation - Forward message to a Private Domain Catch-All

Receiving a message and forwarding to a Private Domain Catch-All requires one API call.

  1. Receive message in a private domain.

Catch-All addresses are considered Mailsac addresses, and internal forwarding is not counted as an additional API call.