---
title: "How does send time optimization work with email throttling?"
slug: "how-does-send-time-optimization-work-with-email-throttling"
description: "Compares send time optimization and email throttling in Insider One: STO picks each user's best send time; throttling caps total hourly email volume."
updated: 2026-06-12T06:23:49Z
published: 2026-06-12T06:23:49Z
canonical: "academy.insiderone.com/how-does-send-time-optimization-work-with-email-throttling"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://academy.insiderone.com/llms.txt
> Use this file to discover all available pages before exploring further.

# How does send time optimization work with email throttling?

[Send time optimization](https://academy.useinsider.com/docs/email-send-time-optimization-1) and [email throttling](https://academy.useinsider.com/docs/internet-service-provider-based-throttling) are separate features that can be used in email campaigns.

Send time optimization calculates the best time for each user to receive messages based on their individual behavior and engagement patterns, considering past open and click events.

On the other hand, email throttling controls the total volume of email sent from your account. It evenly distributes the combined volume of all simultaneously launched campaigns according to the hourly limits you set, ensuring system stability and avoiding ISP rejections.

While send time optimization focuses on determining the optimal time to send messages to individual users, email throttling manages the overall email distribution rate across campaigns.

Your title goes hereSend time optimization and email throttling cannot be used simultaneously.