Email Deliverability

How fast can Instiller deliver emails?

Email messages sent through Instiller use PowerMTA Enterprise from Port25 and that means each of our mail servers has the potential to deliver up to 1 million emails every hour.

There are times when we burst through that level of performance and we’re able to deliver more than 1 million emails per server per hour but in terms of being able to say how long an email campaign will take to deliver, it’s never a simple answer.

Email marketers are in control

The only thing Instiller (or any other ESP) can control is the infrastructure of the solution.

Instiller has built-in features that help ensure best practice is being followed and there’s automation to take care of some list hygiene responsibilities.

In reality though, the speed at which emails get delivered is in the hands of you the sender.

What influences delivery speed?

Once you’ve pressed ‘Send’ a number of factors come into play that will impact on the speed of delivery.

All of these related delivery speed considerations can be controlled by you the sender and all it takes is the correct approach plus an investment of time.

Here’s a short list of just a few things that can impact on email campaign delivery speed:

  • How and where your data was collected
    If you start with ‘bad’ data then it’s only going to get worse from that point onwards. Permission is the key and never think a big list means a better list. A clean, responsive, opted-in list is a good list.
  • List quality
    There are always going to be typo’s and errors and that’s largely unavoidable. If your list is heavily populated with generic sounding email addresses like ‘support@’, ‘accounts@’ or you’ve got a ton of academic and disposable email addresses in there then you might run into issues.
  • Old or unresponsive data
    This might not directly impact on delivery speed but always avoid sending to email addresses that never open or click your emails. In part it’ll help you to avoid Spam traps and you’ll more than likely see a lower complaint rate. Better engagement will improve your sender reputation and in turn your ability to deliver emails faster.
  • Best practice
    Email authentication using DKIM and SPF is the place to start, but don’t stop there. Getting everything in tip-top shape by following best practice doesn’t take any longer than doing things badly. Good marketers get good results. Simple.
  • Email content
    This sounds pretty obvious but make sure what you’re sending is going to be well received. Design is subjective but message composition and quality of content apply across the board. Do lots of testing, use Litmus and don’t overlook responsive email design.

What part do IP addresses play?

There’s more to IP addresses than only looking at things from a delivery speed point of view. For the purposes of this though, let’s just stick to what we’re talking about.

If you send an email campaign that contains 100,000 Microsoft email addresses and the virtual mail server configuration is set to allow delivery of 40,000 emails per domain per IP address per hour then its going to take at least 2.5 hours to deliver those messages using 1 IP address.

Emails to other domains will be sent at the same time because the rates are per domain so potentially you can deliver hundreds of thousands per hour.

Delivery rate throttling

Instiller offers the option to throttle the speed of delivery so that the number of messages sent per hour for an email campaign can be slowed down.

It’s a very handy option when you want to control the rate of response but obviously it will slow down the overall speed of delivery.

Mail server configuration and real-time feedback from ISPs can also impact on email delivery speed:

  • Automatically – ISPs tell our mail servers to ‘slow down’
    If (or any other ISP) doesn’t like what you’re sending it or it’s unsure about your sender reputation then it will instruct our mail servers to slow down. When that happens we listen, and the rate at which emails are delivery is dramatically lowered. It may even result in no emails being delivered for a period of time. In extreme cases, it could even mean you’ve been blocked and delivery will stop completely.
  • Manually – Virtual MTA configuration
    Each Instiller solution has it’s own ‘virtual’ mail servers. Setup can be individually customised and that’s exactly what we do so that sender reputation is matched to how many emails are sent to each ISP per IP address per hour. In our experience a cautious approach provides the best and most sustainable results over time as sender reputation grows through regular sending, user engagement and following best practices.

What others say

We’d love it if Instiller could totally control the speed of delivery so that everyone enjoyed email delivery of 1 million+ emails per hour.

The fact is, we can’t and here’s an article from Return Path that whilst it’s a few years old still rings true –

Other useful posts

Some of the topics mentioned above may be new to you so to help here’s a few related articles that you will find useful:

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