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What is Email Throttling?

Email throttling is sending your emails in batches instead of sending them all in the one go and risk being marked as spam or getting soft bounces. It’s common practice amongst email marketers and is supported by ESPs.

For example, you may have a list of 1,000 contacts you would like to send to. You might then split them into batches of 250 over 4 hours.

Tip: If you have a list of over 250, you should be practising segmentation. Segmentation also means your audience receives content they want to receive, thus potentially raising your overall engagement rates.

What is Meant by Throttling?

So, we have covered what email throttling is, but what is meant by the word ‘throttling’. 

The word is defined as the activity or process of limiting the bandwidth available to users of an electronic communication systems (such as the Internet). Essentially throttling means restricting in segments in which somebody receives something.

Why Should I Throttle My Emails?

Some ESPs enforce a daily send limit to ensure their customer’s emails are prevented from being marked as spam. This is something which Swift Digital closely monitors via our email deliverability team.

ISP (Internet Service Providers) also monitors the number of sends and can sometimes limit the number of emails they receive from the one IP within a specific timeframe. This is again to prevent spam.

There’s no authoritative source on what limits each ISP uses, but a few factors are involved. These factors are:

  • abuse complaints
  • subscriber engagement (open rate, CTR, CTOR)
  • bounce rates
  • spam trap hits

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Throttling your email and practising email throttling sends in batches of 500, 1000, 1500, 2000 etc. will help avoid spam traps and reduce the number of soft bounces you receive when sending an email.

Email Throttling Best Practices

  1. Use an ESP to Throttle Emails

  2. Throttle Between 500 – 10,000

  3. Segment Your Data

1. Use an ESP to Throttle Emails

If you decide you want to throttle your emails, the first thing you need to do is ensure you are sending your emails out from an ESP (Email Service Provider). 

Most reputable email service providers will have an option for you to throttle emails. Some ESP’s control this on your behalf, whilst others leave it in the hands of you. You must decide whether you want a third party controlling your data or not. 

2. Throttle Between 500 - 10,000

The number you throttle your emails by really depends on the size of the list you are sending to. The bigger the list, the larger the email throttling amount. Normal throttling size is between 500 and 15,000.

3. Segment Your Data

Common email marketing best practice is to segment your data. You can segment your information in a way that particularly suits your brand.

For example, you could segment your data based on age, sex, location, interests, state, country, domains, responses, etc. Segmenting your data will indeed create targeted lists. These lists will likely be smaller than the original list and may not require you to throttle your email.

Segmenting your data also means that you can send your audience content that they want to receive based on their preferences. Thus, this may result in increased engagement levels.

How Do I Throttle My Emails?

Each ESP has its way of assisting you in throttling your emails. Some ESPs even take it upon themselves to throttle their customer’s emails if they feel it is necessary. You will likely find the throttling feature at the publishing stage of sending your email. Here, you will be given the option of how much you want to throttle your emails by. 

Email throttling is handled differently depending on what ESP you are using. It would be worth speaking with your account manager of your email marketing platform to understand how to throttle your emails and to also know if you have total control over email throttling or if the email marketing platform intervenes in this.

Swift Digital and Email Throttling

Swift Digital leave email throttling in the hands of the customer. This means that you have free rein to decide how and when you would like to throttle your emails. There are options for throttling between 500-and 15,000 emails when sending. 

Swift Digital’s email deliverability team keeps a keen eye on how the emails are distributed throughout the week and will advise and inform the clients if we believe an email requires throttling for a send. This support is provided by account managers and our dedicated support and deliverability team.

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