March 12, 2024

Email Throttling for Deliverability & Email Marketing

The complete guide on email throttling for deliverability & throttling email marketing. Including examples of what an email throttling plan looks like.

Email Throttling for Deliverability & Email Marketing

Having clear controls and governance around the flow of outbound emails that are sent from your sales domains is critical to ensure they reach their intended recipients and not spam folders. 

Previously, in email marketing, throttling has been referred to as: what happens when the receiving email provider limits the number of incoming emails they accept from a specific sender. However, in the context of outbound email, throttling is the practice of the sender placing limits on how many emails are sent from their sequencing solution, to avoid deliverability issues.

With Allegrow’s new email throttling approach, your team can proactively control sending limitations to improve deliverability in outbound sales rather than reactively having email providers block your incoming messages. This article dives into new throttling functionality while exploring both why and how email throttling can impact your deliverability across the following topics:

- What is Email Throttling?
- Why Sending Spikes Hurt Deliverability
- What Should an Email Throttling Plan Look Like?
- Picking the Correct Target Email Limit
- How to set up email throttling
- Summary for throttling email marketing and outbound 

What is Email Throttling?

Email throttling is the practice of strategically regulating the number of emails sent within a given timeframe to prevent sending spikes that can harm deliverability. By controlling the send rate, businesses can avoid exceeding the sending limits imposed by email service providers (ESPs) and reduce the risk of being flagged as spam​​.

In the past, many platforms have referred to email throttling in the context where email providers limit the number of incoming emails they’ll allow recipients to receive from you leading to soft bounces.

In the context of outbound email, organizations are now placing specific throttling in place on outbound emails they send. This helps avoid poor deliverability and damaged domain reputation by avoiding sending spikes and unsafe levels of outbound email. 

Why Sending Spikes Hurt Deliverability

Email providers see sharp increases in sending volume as a high-risk signal. Substantial increases in email volume indicate automated activity and a greater likelihood of account compromise. Therefore, if engagement is generally low as your volume increases at a fast rate, it’s likely that email providers will filter your traffic into spam folders or even block your outbound emails in some cases. 

As outbound emails are already more likely to have negative engagement, low engagement, or bounces, it’s vital that to maintain good deliverability, this type of email traffic is throttled more aggressively than other forms of email traffic your team might send. This means you should aim to have consistent limits that can adapt based on the age of a mailbox and it’s current sender reputation. 

Examples of the most common situations where sales team members exceed a safe sending limit and spike their volume are:

  • When general limits have not been placed on a reps mailbox meaning they can send thousands of outbound emails inside a 24hr period. 
  • When reps return from PTO and resume sending at the same limit they were previously, this creates a spike due to the inactivity and lack of a customized limit. 
  • When a new sales rep joins the company and immediately sends the same volume as existing reps, without ramping their limits and activity gradually. 

Although most automation providers have the facility for group limits to be set, very few have the capability to create throttling plans that dynamically change based on the type of throttling plan the rep has been assigned. This is where Allegrow steps in to provide additional deliverability controls for high-functioning sales teams. 

What Should an Email Throttling Plan Look Like?

A well-structured email throttling plan accounts for a target daily email limit as the final result of the throttling period. While planning and enforcing a gradually increasing email limit day-by-day over a defined period of time - this is known as the throttling period. 

Specifically for outbound emails, you’ll want to avoid day-over-day increases in throttling limits higher than 2x the prior day's limit. Therefore, an example of a throttling plan for a new sales rep to reach a target limit of 52 emails per day over a 60-day throttling period can be visualized below:

Picking the Correct Target Email Limit

Determining the right email limit involves a deep understanding of your ESP's policies, historical campaign data, and current engagement metrics. Allegrow suggests tailoring your email volume not just to ESP guidelines but also to the engagement levels of your audience. 

Outbound emails carry the highest level of sending risk. Therefore, their sending limits should be closely controlled and lower than the sending limits you have for opt-in lists. Some general guidance on selecting a limit depends on your level of risk tolerance while accounting for the age of the mailbox and domain you send from. 

Throttling Use-Cases

Effective email throttling impacts various aspects of sales and marketing strategies. From onboarding new sellers to utilizing a different domain, and customizing sending limits for different roles; throttling limits provide governance and control over outbound email activity. 

Onboarding Sellers

For new team members, a gradual increase in email volume allows them to adapt to your company's outreach strategy while maintaining high deliverability standards. This "ramping" schedule prevents new accounts from being flagged due to sudden activity spikes​​.

Reviving Suspended Accounts

Accounts returning from suspension or periods of inactivity require a cautious approach to reactivation. A throttled send rate prevents the risk of re-suspension by avoiding sudden increases in email volume, thus safeguarding your sender reputation​​.

Customizing Limits for Different Rep Roles

Different team roles may necessitate distinct email outreach strategies. For instance, account executives might have a higher sending threshold than sales development reps due to the nature of their outreach. Therefore, with Allegrow’s throttling feature, you can manage these limits and throttling schedules effectively across your outreach team. 

How to set up email throttling

Throttling can be set up by creating a day-by-day schedule plan yourself, in Excel, then enforcing those limits manually in your sending provider. However, this is hard to manage and takes a lot of time and effort even using free resources like the DIY throttling calculator here

Therefore, Allegrow can automate this entire process for users as a starting point. Setting up throttling across your team using Allegrow following our documentation here is simple with the following steps:

  • Select which users you want to throttle activity for. 
  • Select the limit and relevant throttle for each of those users. 
  • Then sit back and watch as the limits for each user dynamically progress in Outreach. 


In conclusion, throttling your email activity proactively by creating sensible limits for each sending use case means you are less likely to experience deliverability issues. The plan you implement for throttling will vary based on your sending use case and system. Sending to opt-in lists through systems like Mailchimp or Hubspot can be carried out with throttling features and segmentation best practices inside those applications. Whereas cold email sending has a higher level of risk and therefore requires more strict per-user throttles, this is where custom deliverability applications like Allegrow provide revenue operations teams with additional support and safeguards.