One of our values at Kit is to work in public. We strive for transparency, which is why we share information that is typically kept private, such as our finances.
One commonly asked question by creators looking for a new email marketing platform is, “How is your email deliverability?”
Here is our monthly deliverability report to answer that question:
If you missed previous Deliverability reports, you can check them out below:
In December, Kit sent over 1.4 billion messages (1,454,145,636 to be exact).
When messages are sent, they can be delivered, or they can bounce. For more details on how email deliverability operates, check out our blog post here. But for a little TLDR—the more messages delivered, the better!
It’s inevitable for some messages to bounce due to invalid addresses, full mailboxes, etc., but a good delivery rate indicates healthy deliverability for Kit. We consider a system-wide delivery rate of 98% and above to be very healthy.
In December, our system-wide delivery rate was 99.7%.

This high delivery rate indicates a healthy reputation for Kit, which gives our customers a solid foundation for their email deliverability. To get even more detailed about how well we’re performing, it helps filter down by mailbox provider.
Here are the top 5 domains Kit sends to in terms of volume:
1. Gmail.com
885 million messages
Delivery rate: 99.9%
2. Yahoo.com
152 million messages
Delivery rate: 99.9%
3. Hotmail.com
103 million messages
Delivery rate: 99.9%
4. AOL.com
35 million messages
Delivery rate: 99.9%
5. Outlook.com
14 million messages
Delivery rate: 99.9%
The average open rate of all emails sent through Kit was 37.3%.
Senders often ask how their open rates stack up to others. The truth is, open rates can vary greatly depending on your industry and audience type (B2B vs. freemail addresses, for example). However, here’s a general scale you can use to measure your performance:

I talk more about open rates and why they aren’t always reliable in this article.
We are seeing open rates increase globally due to the recent Apple iOS updates.
In case you missed it, Apple made some privacy-focused changes to their email clients that causes open-tracking pixels to be loaded automatically, whether or not the message was actually opened by the subscriber. This means that open rates are falsely inflated when subscribers are using an Apple mail app to receive their emails. You can read more about this here.
Before the Apple changes, the average open rate across Kit accounts was 30%. As of December, the average open rate across Kit accounts is 37.3%. We expect to continue to see open rates rise as iOS15 adoption continues to increase.
The average click rate across Kit accounts was 5.1%.
We calculate click rate by dividing the number of subscribers who clicked a link by the total number of subscribers who received the email.
Similarly, the average click-to-open rate was 12%. This is calculated by dividing the number of subscribers who clicked a link by the number of subscribers who opened the email.
Our system-wide complaint rate remained over 10x lower than the industry standard
A complaint is when a subscriber marks a message as spam. An elevated complaint rate is a signal that the sender’s quality of mail isn’t good. We have a team dedicated to ensuring that the recipients want the mail sent from Kit.
In the email industry, a complaint rate of less than 0.1% is seen as healthy. Kit’s complaint rate in December was 0.012%, which speaks to the high quality of mail sent by our customers and the healthy reputation of our infrastructure.
Deliverability tip of the month:
Want to grow your email list? Consider using a referral program! To learn more about how referral programs work and how they can help you expand your audience, check out this episode of Deliverability Defined.
The Deliverability Defined Podcast is back!

We’re so excited to be back for season 3 of Deliverability Defined. You can check out the episodes we released in December below:
- Episode 2: Growing your list with a referral program
- Episode 3: How to serve multiple audience types
- Episode 4: Protecting your email list and reputation
- Episode 5: Why some subscribers don’t confirm their opt-in