Email Deliverability Statistics 2023: What Percentage of Emails Went to Inbox?

Email Deliverability Statistics: Delivery per Top 5 ISPs

Let’s start with the average email delivery data for the major mailbox providers regardless of an email service provider used, the volume of emails sent, or the type of email messages (subscription or cold).

Our calculation gives these email delivery statistics when the messages are sent to the five major ISPs:

AOL average delivery rates:

• Inbox: 38.3%;
• Spam: 34.2%;
• Undelivered: 27.5%.

Yahoo average delivery rates:

• Inbox: 38.6%;
• Spam: 34.8%;
• Undelivered: 26.6%.

Gmail average delivery rates:

• Inbox: 70.7%;
• Spam: 14.8%;
• Undelivered: 14.5%.

Outlook average delivery rates:

• Inbox: 39.9%;
• Spam: 34.7%;
• Undelivered: 25.3%.

Hotmail average delivery rates:

• Inbox: 40.6%;
• Spam: 33.6%;
• Undelivered: 25.8%.

So far, Gmail showed the best deliverability in the Inbox and the lowest percentage of undelivered – mostly blocked – messages. But the numbers may change as the Gmail new email sender standards became effective starting from February 1st, 2024.

Email Deliverability Statistics: Delivery per Email Service Providers

We were often asked what the best email service provider (ESP) in terms of deliverability was. That’s a good question indeed because the reputation of the sending IP address is counted for email placement. 

Each ESP is using its own set of IP addresses, which are shared between numerous senders. The reputation of these IPs is built based on the sending habits of all the senders. 

Thus, the way an ESP manages the clients’ mailing lists (unsubscribes, complaints, and bounce emails) and controls what types of messages and to whom the clients send has an impact on the reputation of the IPs.  

Before we dive into email deliverability statistics per ESP, we want to share the data about the most popular email service providers used by GlockApps customers.

The percentage of GlockApps customers using different email service providers is as follows:

1. Google – 41%
2. Mailgun – 13%, Outlook – 13%
3. Amazon SES – 7%
4. SendGrid – 5%
5. Klaviyo – 4%
6. GoDaddy – 2%, Customers.ai – 2%, MailChimp – 2%, Cp20.com – 2%, teneo.be – 2%
7. AWeber, – 1%, ConvertKit – 1%, Brevo – 1%, Mailjet – 1%, GetResponse – 1%, MailerLite – 1%, Hubspot – 1%, ActiveCampiagn – 1%, Salesforce – 1%.  

The percentage of customers using other email service providers such as Sendinblue, Mimecast, Keap, and other makes less than 1%.

Our analysis of the emailing statistics for the fourth quarter of 2023 shows that the highest deliverability – in average 50+% emails went to Inbox – was demonstrated by these ESPs:

ESP	Inbox Average (%)	Spam Average (%)
Mimecast	75,8	4,5
DotMailer	65,0	4,0
AWeber	61,0	6,2
ActiveCampaign	60,9	8,7
Hubspot	59,3	9,3
Klaviyo	57,8	14,0
MailChimp	57,03	13,1
Amazon SES	55,1	23,6
Outlook	54,6	23,8
GoDaddy	53,7	19,4
Google	53,3	28,5
MailerLite	52,6	16,0

Email Deliverability Statistics: Average Deliverability per Volume

Email experts agree that consistency in email sending is important for good deliverability. In email marketing, consistency means sending an approximately same volume of messages at a regular interval. Thus, if you plan email campaigns about your blog or product update, you’ll want to schedule them for a particular day of week or month. Consistent senders are treated as trusted more often than inconsistent marketers. 

Now, what about the volume? Does the volume of emails sent per month affect delivery? 

We divided all GlockApps users into five groups based on the number of email messages sent per month. Below we’re sharing the average emailing statistics for each group.

Email Deliverability Rate: 1 – 10,000 Emails per Month

From what we’ve got, the highest average Inbox placement rate in this sender group was demonstrated for these ISPs:

ISP	Inbox Average (%)	Spam Average (%)
Amazon Workmail	78,97	1,23
GMX.com	69,82	11,12
Exchange (Office 365)	65,79	12,85
G Suite (Google Workspace)	65,68	11,12
Gmail (non-interactive)*	64,76	10,32
Gmail (legacy)**	59,30	19,57

*Gmail (non-interactive) are the seed email addresses that we started using for tests in the Inbox Insight v2.0. These are relatively young mailboxes – 3 months old.

**Gmail (legacy) are the seed email addresses moved to the new seed lists from the old Inbox Insight tool. These are aged and well warmed up mailboxes that have been receiving email messages for years.

The reason we keep two categories of seed email addresses for Gmail is that Gmail is sensitive to user engagement and the volume of sent emails more than other ISPs. 

Email Deliverability Rate: 10,001 – 50,000 Emails per Month 

The next group is the senders with 10,001 – 50,000 messages per month. In this group, the ISP that delivered more than 50% emails in the Inbox are:

ISP	Inbox Average (%)	Spam Average (%)
Amazon Workmail	80,09	0,95
GMX.com	71,01	13,25
Gmail (non-interactive)	68,99	10,40
G Suite (Google Workspace)	68,29	10,20
Exchange (Office 365)	64,13	13,99
Gmail (legacy)	61,85	15,55
Hotmail	50,90	28,79
Outlook	50,22	29,11

The ISP that placed the highest number of emails in Spam are AOL (36,12%) and Yahoo (33,37%).

Email Deliverability Rate: 50,001 – 200,000 Emails per Month

Senders in this group had their email communications delivered in the Inbox most often with the following ISPs:

ISP	Inbox Average (%)	Spam Average (%)
Amazon Workmail	82,89	1,28
Gmail (non-interactive)	73,44	10,04
Exchange (Office 365)	71,14	11,54
GMX.com	71,07	10,94
G Suite (Google Workspace)	69,71	12,61
Gmail (legacy)	63,38	18,28
AOL	59,52	24,87
Yahoo	57,66	26,35
Hotmail*	54,10	28,05
Outlook*	54,00	28,37
Att.net*	51,16	27,63

*The top three providers that filtered the highest number of emails as spam.

Email Deliverability Rate: 200,001 – 1,000,000 Emails per Month

For large email volume senders, the average Inbox placement rate higher than 50% was demonstrated by these ISPs:

ISP	Inbox Average (%)	Spam Average (%)
Amazon Workmail	81,04	0,30
GMX.com	80,01	3,82
Gmail (non-interactive)	70,48	9,54
G Suite (Google Workspace)	63,81	12,26
Exchange (Office 365)	59,83	16,94
Yahoo	53,24	28,42
AOL	53,04	28,87
Att.net	52,78	25,91
Outlook	50,14	27,81

Email Deliverability Rate: 1,000,000+ Emails per Month

Very large email volume senders emailing starting at 1,000,000 messages per month got the average rates as follows:

ISP	Inbox Average (%)	Spam Average (%)
Amazon Workmail	79,60	0,71
GMX.com	75,05	9,28
Gmail (non-interactive)	70,68	9,44
Exchange (Office 365)	67,84	10,28
G Suite (Google Workspace)	64,39	10,29
Gmail (legacy)	58,44	17,43
AOL	56,60	21,12
Yahoo	55,89	19,45
Outlook	55,64	20,79
Att.net	54,84	20,65
Hotmail	54,82	21,24
Zoho	27,95	6,37

The Takeaway

What we’ve learned during the analysis of our email deliverability statistics for the fourth quarter of 2023 is that the volume of emails sent has a little impact on deliverability. Whether you are a small or large email sender, the key is consistency and adherence to email sender guidelines advertised by each ISP. 

Although the data in this article can be a useful point of reference, it’s important to check back frequently because email deliverability is a constantly changing field with varying numbers every year.

If you are involved in email marketing, it is essential to be educated about deliverability and understand the various factors that impact email deliverability rates. It is important to be aware of the recommended email practices published by different ISPs to get the highest possible deliverability rates and use good deliverability monitoring tools to perform your deliverability check on a regular basis.