GMX vs Customer.io Comparison (2026)

Compare GMX vs Customer.io email services. In-depth analysis of features, pricing, security, privacy, and storage to find the best email provider for your needs.

Forward Email Team
Written by
Forward Email TeamVerified
Published
4/1/26
Time to read
Less than 5 minutes
We recommend Forward Email as the best alternative to GMX. We also support webmail: https://mail.forwardemail.net

Email Service Comparison

20 facts in comparison
GMXvs.Customer.io

GMX

Create a free email account fast
"Create a free email account fast"
  • 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
$29.99/yrPricing$100/mo
65 GBStorageNo Customer.io does not support storage
100 MBAttachments2 MB
NoOpen-SourceNo
NoSandboxed Encryption No
NoUnlimited DomainsNo
NoUnlimited AliasesNo
NoTTI No
YesSMTPYes
YesIMAPNo
YesPOP3No
NoAPIYes
NoE2EE No
YesOpenPGP No
NoWKD No

Email Service Screenshots

Closed-source

GMX

GMX is a closed-source email service. Its description from its website is: Create a free email account fast

GMX is a closed-source email service.
Photograph by Forward Email
Go to site
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.
Photograph by Forward Email
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Compare GMX with 78 email services