Customer.io vs Tutanota Comparison (2025)

What are the differences between Customer.io and Tutanota?

Forward Email Team
Written by
Forward Email TeamVerified
Published
7/1/25
Time to read
Less than 5 minutes
We recommend Forward Email as the best alternative to Customer.io.

Email Service Comparison

20 facts in comparison
Customer.iovs.Tutanota

Customer.io

Send messages people actually want to receive using real-time customer data
"Send messages people actually want to receive using real-time customer data"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
vs.

Tutanota

Secure, green and ad-free. Email to feel good about
"Secure, green and ad-free. Email to feel good about"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
$100/moPricing€36/yr
No Customer.io does not support storageStorage20 GB
2 MBAttachments25 MB
NoOpen-Source❌ Tutanota claims to be open-source, but their back-end is actually closed-source
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
YesSMTPNo
NoIMAPNo
NoPOP3No
YesAPINo
NoE2EE No
NoOpenPGP ⚠️ Tutanota does not support PGP
NoWKD No

Email Service Screenshots

Closed-source

Customer.io

Customer.io is a closed-source email service. Its description from its website is: Send messages people actually want to receive using real-time customer data

Customer.io is a closed-source email service.
Photo by Forward Email
Visit Website
Closed-source

Tutanota

Tutanota is a closed-source email service. Their official description reads: Secure, green and ad-free. Email to feel good about

Tutanota is a closed-source email service.
Screenshot by Forward Email
Visit Website

Compare Customer.io with 78 email services