N‑able Mail Assure vs Customer.io Comparison (2026)

What are the differences between N‑able Mail Assure and Customer.io?

Forward Email Team
Written by
Forward Email TeamVerified
Published
2/1/26
Time to read
Less than 5 minutes
We recommend Forward Email as the best alternative to N‑able Mail Assure. We also support webmail: https://mail.forwardemail.net

Email Service Comparison

20 facts in comparison
N‑able Mail Assurevs.Customer.io

N‑able Mail Assure

Email protection to help you secure and scale
"Email protection to help you secure and scale"
  • 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
Requires you to talk to a sales teamPricing$100/mo
Requires 3rd partyStorageNo Customer.io does not support storage
Depends on inbound/outbound (e.g. 10 MB)Attachments2 MB
NoOpen-SourceNo
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
❌ Requires 3rd partySMTPYes
❌ Requires 3rd partyIMAPNo
❌ Requires 3rd partyPOP3No
YesAPIYes
NoE2EE No
NoOpenPGP No
NoWKD No

Email Service Screenshots

Closed-source

N‑able Mail Assure

N‑able Mail Assure is a closed-source email service. Their website says: Email protection to help you secure and scale

N‑able Mail Assure is a closed-source email service.
Photo by Forward Email
Visit Website
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

Compare N‑able Mail Assure with 78 email services