Tutanota vs Customer.io Comparison (2025)

What are the differences between Tutanota and Customer.io?

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 Tutanota.

Email Service Comparison

20 facts in comparison
Tutanotavs.Customer.io

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
vs.

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
€36/yrPricing$100/mo
20 GBStorageNo Customer.io does not support storage
25 MBAttachments2 MB
❌ Tutanota claims to be open-source, but their back-end is actually closed-sourceOpen-SourceNo
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
NoSMTPYes
NoIMAPNo
NoPOP3No
NoAPIYes
NoE2EE No
⚠️ Tutanota does not support PGPOpenPGP No
NoWKD No

Email Service Screenshots

Closed-source

Tutanota

Tutanota is a closed-source email service. Its description from its website is: Secure, green and ad-free. Email to feel good about

Tutanota is a closed-source email service.
Photo by Forward Email
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Closed-source

Customer.io

Customer.io is a closed-source email service. Their official description reads: Send messages people actually want to receive using real-time customer data

Customer.io is a closed-source email service.
Screenshot by Forward Email
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Compare Tutanota with 78 email services