Customer.io vs Cisco Secure Email Defense Comparison (2025)

What are the differences between Customer.io and Cisco Secure Email Defense?

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.Cisco Secure Email Defense

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.

Cisco Secure Email Defense

Advanced protection to safeguard your inboxes
"Advanced protection to safeguard your inboxes"
  • Hardenize Test
  • Internet.nl Site Test
  • Internet.nl Mail Test
  • Mozilla HTTP Observatory Grade
  • Qualys SSL Labs SSL Server Test
$100/moPricingRequires you to talk to a sales team
No Customer.io does not support storageStorageUnknown
2 MBAttachments100 MB
NoOpen-SourceNo
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
YesSMTP❌ Requires 3rd party
NoIMAP❌ Requires 3rd party
NoPOP3❌ Requires 3rd party
YesAPIYes
NoE2EE No
NoOpenPGP No
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.
Screenshot by Forward Email
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Closed-source

Cisco Secure Email Defense

Cisco Secure Email Defense is a closed-source email service. According to their website: Advanced protection to safeguard your inboxes

Cisco Secure Email Defense is a closed-source email service.
Photograph by Forward Email
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Compare Customer.io with 78 email services