Spam Scanner vs Customer.io Comparison (2026)

What are the differences between Spam Scanner 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 Spam Scanner. We also support webmail: https://mail.forwardemail.net

Email Service Comparison

20 facts in comparison
Spam Scannervs.Customer.io

Spam Scanner

Spam Scanner is the best anti-spam, email filtering, and phishing prevention service
"Spam Scanner is the best anti-spam, email filtering, and phishing prevention service"
  • 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
Free (built-in to Forward Email)Pricing$100/mo
Requires 3rd partyStorageNo Customer.io does not support storage
UnknownAttachments2 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

Spam Scanner

Spam Scanner is a closed-source email service. Their website says: Spam Scanner is the best anti-spam, email filtering, and phishing prevention service

Spam Scanner is a closed-source email service.
Photo by Forward Email
Visit Website
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
Visit Website

Compare Spam Scanner with 78 email services