Mailjet lets you set a Daily Send Limit (DSL) per API key to control how many messages that key can send in a day. This helps you split volume across integrations/subaccounts, reduce risk if a key is misused, and manage ramp-up safely.

Where to find the Daily Send Limit

1. Go to Account → API Keys (API Key Management).

2. You’ll see:

   • Default Daily Send Limit (applies by default)

   • A Daily Send Limit value for the Primary API Key

   • A Daily Send Limit value for each Subaccount API Key

Default Daily Send Limit: what it is (and what it defaults to)

The Default Daily Send Limit is the baseline limit used for all API keys unless you set a custom limit for a specific key.

Default values by plan:

• Contract (Custom) accounts: Default is Unlimited.

• All other paid accounts: Default is 5× your subscription sending limit.

Set or update the Default Daily Send Limit

1. In Default Daily Send Limit, click the pencil (edit) icon.

2. Enter the daily limit you want.

3. Save your changes.

Set a Daily Send Limit for a specific API key

You can override the default and apply a different Daily Send Limit to the Primary key or any Subaccount key.

1. Locate the key under Primary API Key or Subaccount API Keys.

2. In the Daily Send Limit column, click the pencil (edit) icon.

3. Set the limit.

4. Save.

Remove a key-specific limit (use the default again)

1. Next to the key, click the trash icon.

2. The key will fall back to the Default Daily Send Limit.

What happens when the Daily Send Limit is reached?

When an API key reaches its Daily Send Limit:

• The API key enters a Quarantine state.

• In the app, you should see:

  • A banner notifying you that the Daily Send Limit has been reached.

  • On the API Key Management page, the affected key should be shown as rate limited.

How to lift the limit after it’s reached

If your API key is in quarantine due to the Daily Send Limit being reached, you can resolve it by:

1. Navigating to Account → API Keys.

2. Finding the affected API key.

3. Increasing its Daily Send Limit.

Best practices

• Use separate subaccount keys for different apps/clients so one integration can’t impact another.

• Avoid setting Daily Send Limit to 0 unless you intentionally want to block sending.

• Start with a conservative Daily Send Limit for new integrations, then increase as you validate sending behavior.

• If you’re on a non-Custom plan and want an “unlimited” cap, set a very large number that you’ll realistically never reach (since Unlimited is only available for Contract accounts).