As a marketing professional, I'm relentlessly curious about the best time to send my email campaigns. With the average business person sending or receiving 112 emails per day, it’s hard to get people’s attention if you don’t time them right. While there have been countless studies on the subject, I’ve never found any conclusive evidence on what time of day or day of week is the best time to send email.

Recently, one of our company founders was talking with Seventh Sense, a new data analytics company that focuses on personal email habits and whose product integrates with our marketing automation system, Hubspot.

We were a bit skeptical at first, but decided to test it out and were surprised and elated with the results. Below are the details of how we tested the platform and what we found.

Testing Parameters
We’re obsessive about A/B testing and Seventh Sense has built some cool tools that ensure the A and B audiences are equal in terms of amount of engagement and most recent time of engagement in marketing emails. We also needed to make sure that the lists we were sending to would have statistical relevance, so decided to test it with a large mailing (>57K contacts).

The charts below provide detail on each test mailing and segmentation of contacts that had previously engaged with a piece of our content.


Once we created two equal audiences (a very simple process), we used two delivery approaches to test whether Seventh Sense’s method of personalizing the delivery time through Hubspot would have an effect. For further clarification, we used our normal way of sending on one specific day/time as our control as this is the way we have always delivered our email campaigns. 

How Seventh Sense Works

Seventh Sense uses the Hubspot workflow engine to initiate the delivery of emails, so all of our reporting, email creation and delivery is still handled by Hubspot. Otherwise, this would have been a non-starter for us.

Delivery Method

  • It personalizes the delivery time for contacts with historical data. For contacts with a history of receiving, opening and engaging in email, the system crunches that data and picks the most optimal delivery time for each individual within a user-defined time window. If an optimal time does not exist within the time window, Seventh Sense will predict an optimal time.

  • It randomizes the delivery time for contacts without historical data. For new contacts or contacts who have never engaged, the system randomizes the delivery to each contact, between 8:00AM and 8:00PM EST. The goal is to discover that ideal delivery time for contacts who have never engaged in the past—the time they’ve specifically set aside to go through their inboxes.

Mailing Timeline

  • Batch delivery took place on Wednesday, September 9 at 9:00AM, which also happens to be our peak engagement time as we wanted to test Seventh Sense against what we’ve experienced to be the best time.

  • Using Seventh Sense, we decided on a 24-hour delivery period to reduce day of week variables. This took place from 12:01AM EST to 11:59PM EST on Wednesday, September 9th.

Our results were dramatic. We saw an open rate increase of 54.08% using Seventh Sense’s method of personalizing the delivery time compared with our normal batch delivery method. We also saw a click rate increase of 36.44% and a click magnification (click per contact) increase of 17.69%.

Below is an annotated screenshot of our Hubspot email dashboard.


These results were astounding to us, especially considering that the only thing required to see these types of increases is to spend an extra couple of minutes each time we send out a campaign. Seventh Sense also continually learns and adapts as new and existing contacts engage. In turn, we’re experiencing more conversions on our landing pages, which is leading to more leads for our salespeople to follow up on. We’re quite thankful that we discovered Seventh Sense.

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