Customer.io vs Posteo Comparison (2026)
Compare Customer.io vs Posteo email services. In-depth analysis of features, pricing, security, privacy, and storage to find the best email provider for your needs.
Email Service Comparison
20 facts in comparison| Customer.io | vs. | Posteo |
|---|---|---|
Customer.io "Send messages people actually want to receive using real-time customer data" | vs. | Posteo "Green, secure, ad-free" |
| $100/mo | Pricing | β¬1/mo |
| β Customer.io does not support storage | Storage | 2 GB |
| 2 MB | Attachments | 50 MB |
| β | Open-Source | β |
| β | Sandboxed Encryption | β |
| β | Unlimited Domains | β |
| β | Unlimited Aliases | β |
| β | TTI | β |
| β | SMTP | β |
| β | IMAP | β |
| β | POP3 | β |
| β | API | β |
| β | E2EE | β οΈ Opt-in |
| β | OpenPGP | β |
| β | WKD | β |
Email Service Screenshots
Customer.io
Customer.io is a closed-source email service. The official description from its website says, "Send messages people actually want to receive using real-time customer data".
Posteo
Posteo is a closed-source email service. The official description from its website says, "Green, secure, ad-free".
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Custom domain email hosting
Free email forwarding and custom domain hosting that works everywhere.
Custom Domain Email Address
Establish credibility with professional email addresses like you@yourdomain.com.
Unlimited Email Accounts
Create as many domain names and email addresses as your team needs, without extra costs.
Generous 10 GB Email Storage
Ample space for all your important communications and attachments. Pay as you go.
Compatibility & Deliverability
Works with Gmail, Yahoo, Outlook, and adheres to all 2026 email standards for optimal deliverability.
Any device
Access your email anywhere
Our email service works with any device and email client, so you can read your mail from anywhere.
- iPhone & macOS
- Android
- Windows
- Any Email Client
All-inclusive features
No additional fees for must-have features.
- 100% Open-Source Software
- Quantum-Resistant Encryption
- Advanced Email Security
- Reliable Email Sending & Receiving
- Email Archiving & Download
- Integrated Calendars & Contacts
- Bounce & Web Alert Notifications
- Developer-Friendly Email API
- Email Encryption & Message Signing
- Encrypted PGP Forwarding
- Intelligent Spam & Phishing Protection
- Email Standards Compliance
- Forwarding & Secure Delivery
- Safe Web Lookups & Data Protection
- Sandboxed Mailboxes
- Self-Hosted Docker Email
- Zero-Knowledge Architecture
- 99.99% Uptime
Simple pricing
Unlimited domains at every tier.
Start with forwarding, upgrade to real mailboxes, then add team controls. Every tier includes unlimited domains.
- Unlimited inbound email
- Spam protection
- 50 MB attachment limit
- Send Mail As with Gmail
- Catch-all email addresses
- Multiple recipients per alias
- Send emails to webhooks
- Regular expression filtering
Limitations: Email forwarding only, which means you cannot send mailEnhanced Protection
Send & receive as you@yourdomain.com
$3/month for unlimited domainsGet you@domain.com- Everything in Free plus:
- Unlimited aliases ($0/user)
- 10 GB pooled storage
- Secure inbox privacy
- Unlimited outbound (reputation-based)
- Email analytics & insights
- DMARC Reporting
- Send outbound SMTP email
- Developer API access
Best for: Individuals, freelancers, and small businesses- Everything in Enhanced plus:
- Outbound starts at 900/day
- Unlimited team members
- Team permission management
- Shared organizational access
- Priority support requests
- Custom recipient verification
Best for: Collaboration across families, teams, and organizationsEnterprise
For education, universities, alumni, healthcare, government, and custom implementations
$250/month for unlimited domainsContact us- Everything in Team plus:
- Unlimited API requests
- Terms of Use exception for 3rd parties
- Dedicated customer support chatroom
- Enterprise contract agreement sent via DocuSign
- Onboarding assistance and real-time engineering support
Frequently Asked Questions
Common questions about plans.
What's the difference between Enhanced Protection and Team plans?
Enhanced Protection ($3/month) is perfect for individuals who need professional email with sending/receiving capabilities, 10GB storage, and API access. Team plan ($9/month) adds collaborative features like team member management, shared organizational access, and priority support - ideal for families, groups, and businesses.
Can I send and receive emails with the Free plan?
No, the Free plan only supports email forwarding. You can receive emails at your custom domain and forward them to your existing email address, but you cannot send emails directly from your custom domain or store emails on our servers.
Who should choose the Team plan?
The Team plan is perfect for families sharing a domain (like @smithfamily.com), small businesses with multiple employees, organizations needing shared email management, or any group that requires collaborative access to email accounts with proper permission controls.
What does 'unlimited domains' mean?
All plans include unlimited domains at no extra cost. Whether you have 1 domain or 100 domains, you pay the same price. This makes our service cost-effective for users managing multiple websites or businesses.
Do you charge per user/alias like other services?
No! Unlike other email services that charge per user or alias, we include unlimited aliases in our Enhanced Protection and Team plans. Create as many email addresses as you need (info@, sales@, support@, etc.) without additional fees.
Can I upgrade or downgrade my plan anytime?
Yes, you can upgrade or downgrade your plan at any time. When upgrading, you'll get immediate access to new features. When downgrading, changes take effect at your next billing cycle, and you'll retain access to paid features until then.
Trusted by millions
Leading organizations and businesses worldwide rely on our secure and reliable email service.
- Government
US Naval Academy, Government of South Australia, Government of Dominican Republic
- Enterprise
Netflix Games, Disney Ad Sales, Fox News Radio, RCD Hotels
- Open-source
The Linux Foundation, jQuery, Ubuntu, LineageOS, Canonical
- Education
Carnegie Mellon, Cambridge, UMD, UW, Tufts, Swarthmore
Ready to join these organizations?
Why people switch
Trusted for the reasons that matter.
The claims this page makes, backed by people with no reason to flatter us, and a receipt you can check yourself.
Private by architecture
Congrats for fully launching Forward Email β a forwarding service for email that doesn't keep logs or store emails, and which works with ARC to ensure signed forwards don't trip email filters π. I'm a happy user! β€οΈ
Migration is a DNS change
Have now switched email forwarding from MailGun to ForwardEmail.net . Simple and painless (and free!). Just some DNS changes, and it just works. Thanks
One inbox for every address
So they made this cool app that forwards email from your own domain to your Gmail inbox. There is even a catch all option, so sales@, support@, etc all goes to your own inbox. Check it out! It's free! forwardemail.net
