How campaign delivery works

Every sending platform hands its emails to the same network of email providers, and each provider works at its own pace depending on how much traffic it is processing. A provider scans each message it receives, decides where it belongs, and releases it to the inbox once those checks are done.

At Instant, the time you schedule a campaign for is the time dispatch begins. Your emails go out from that point, and each provider delivers them as it works through its own queue, so your shoppers receive them across a period rather than all at one moment.

The times shown in Instant are the point a provider confirmed the email had landed, not the point Instant sent it. This is why a delivery time can sit after your scheduled time even though the email left Instant straight away. Some platforms show the time the email left their system instead, which looks earlier but does not tell you whether it arrived.

To watch a send as it happens, go to Campaigns, open the campaign, and select the Activity tab.

Why might an email be delayed

Delays usually come down to one of three things, and the difference is normally a matter of minutes.

Security and spam checks. Every provider scans incoming mail before deciding where to put it. Some accept an email straight away and then hold it briefly while those checks finish, so it appears in the inbox shortly after it reached the server.

A new sending domain. When you start sending from a domain for the first time, providers have no history with it. They can take a little longer over your mail while they build up a picture of your sending. This settles as you send more.

Very large sends and peak periods. Instant puts your deliverability ahead of everything else. For very large lists, and over peak periods such as Black Friday and Cyber Monday, your emails may be staggered by up to 30 minutes. Releasing a very large volume in one burst is the kind of pattern that leads providers to slow your mail down or filter it into spam, so spacing the send out protects your sending reputation and keeps your emails reaching the inbox. Providers are also handling far more mail than usual at those times, so allow extra time for a campaign to land.

How this may differ per provider

Two shoppers can receive the same campaign at different times depending on who hosts their inbox.

Microsoft, which covers Outlook, Hotmail and Live addresses, checks incoming mail more strictly than most. It commonly accepts an email, holds it while its security scanning finishes, then releases it to the inbox. You will often see Microsoft addresses land after Gmail addresses from the same send for this reason.

Providers do not publish the detail of how this works, including how long they hold mail or what prompts extra checks. Publishing it would tell spammers how to get around it.

How to maximize send times

The most effective option is AI Personalized Send Times. Rather than sending to everyone at one fixed time, Instant sends to each shopper around the time they usually open their email, so your campaign arrives when they are most likely to read it. See How do AI Personalized Send Times work in campaigns?.

If you would rather set the time yourself, you can send at the same local time for every shopper, wherever they are. See Send campaigns in your recipients’ local timezone.

Planning a time sensitive send

Flash sales, countdown offers and competitions rely on shoppers acting in a narrow window, so it helps to plan for some spread in arrival times.

  • Schedule the campaign ahead of the moment the offer opens, so the later deliveries still arrive in time.
  • Set the offer to a fixed end time on your site, with a countdown or a deadline on the landing page, so every shopper sees the same deadline whenever their email arrives.
  • If a promotion depends on order of entry, base it on something other than who clicks first, as delivery order varies by provider.
  • Allow extra time over peak periods and for large lists.

FAQ

Is this specific to Instant? No. Every email service provider works this way, because the final step belongs to the inbox provider rather than the platform sending the email. Klaviyo’s documentation, for example, notes that there is processing time between the scheduled send time and delivery.

Why might my emails be staggered? To protect your deliverability. Sending a very large volume in one burst, particularly over a peak period, can lead providers to slow your mail down or filter it into spam. Where that risk is there, spacing the send out by up to 30 minutes keeps your sending reputation healthy so your emails reach the inbox.

My campaign still says Sending. Has something gone wrong? Not necessarily. A campaign stays in Sending until the last recipient has been processed, so a large list or a campaign using recipient local time will hold that status for a while.

Can I make all my emails arrive at the same time? No. Sending may be spread out to protect your deliverability, and each provider adds its own processing time on top, so arrival is always spread across a period.

Some shoppers got it later than others. Why? Delivery speed varies by provider and by how much mail that provider is handling at the time. Two shoppers on the same list, one on Gmail and one on Outlook, can receive the same campaign at different times.

For more on what happened to each email in a send, see Understanding Your Campaign Deliverability.