Customer.io vs Cisco Secure Email Defense Comparison (2026)

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

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 Customer.io. We also support webmail: https://mail.forwardemail.net

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. Their website says: Send messages people actually want to receive using real-time customer data

Customer.io is a closed-source email service.
Photograph by Forward Email
Go to site
Closed-source

Cisco Secure Email Defense

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

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