EmailEngine vs Unipile: Email API Comparison
Comparing email-focused self-hosted API (EmailEngine) vs multi-channel managed service (Unipile). This guide helps you choose the right solution for your project.
Summary
- Unipile: Fully managed SaaS with multi-channel messaging (Email + LinkedIn + WhatsApp)
- EmailEngine: Self-hosted email-focused solution with flat pricing and data sovereignty
Choose based on your priorities: multi-channel integration vs control and cost.
Quick Comparison Table
| Feature | EmailEngine | Unipile |
|---|---|---|
| Hosting | Self-hosted | Fully managed SaaS |
| Data Storage | Metadata only (in Redis) | Full message copies in Unipile cloud |
| Pricing Model | Flat yearly license | Per-account (3-5 EUR/month) |
| Setup Time | 5-10 minutes | Instant (signup) |
| Data Residency | Your infrastructure | EU (France - Scaleway) |
| Multi-Channel | Email only | Email + LinkedIn + WhatsApp + more |
| Calendar | No | Yes (Google/Outlook only) |
| Webhook Latency | Near-instant | Similar |
| Compliance | Full control | SOC 2, GDPR |
| Support | Community + Direct | Enterprise support |
Key Architectural Differences
Hosting Model
Unipile:
- Cloud-hosted service (SaaS only)
- No infrastructure management
- Automatic scaling
- EU-based data centers (Scaleway, France)
- Trade-off: Vendor dependency, no self-hosted option
EmailEngine:
- Self-hosted on your infrastructure
- You manage servers, scaling, backups
- Full control over deployment
- Trade-off: Operational responsibility
Best for:
- Unipile: Teams without DevOps capacity, need multi-channel messaging
- EmailEngine: Teams with existing infrastructure or strict data requirements
Data Storage Architecture
Unipile:
- Stores: Message copies, metadata, attachments
- Location: EU-based servers (Scaleway, France)
- Advantages: Fast reads, unified multi-channel inbox
- Disadvantages: Data stored on third-party servers
EmailEngine:
- Stores: Message UIDs, flags, folder structure only
- Advantages: Minimal data exposure, no third-party storage
- Disadvantages: Slightly slower first-time reads
Best for:
- Unipile: Multi-channel communication apps, EU data residency requirements
- EmailEngine: Maximum privacy, full data control on your own infrastructure
Scope of Integration
Unipile:
- Email (Gmail, Outlook, IMAP)
- LinkedIn messaging (including Recruiter & Sales Navigator)
- WhatsApp (Classic and Business)
- Instagram Direct
- Facebook Messenger
- Calendar (Google, Outlook)
- X (Twitter) messaging
EmailEngine:
- Email only (Gmail, Outlook, IMAP/SMTP)
- Deep email protocol integration
- Advanced email features (bounce detection, delivery tracking)
Best for:
- Unipile: Sales outreach, recruiting, CRM integrations needing multiple channels
- EmailEngine: Email-focused applications requiring maximum control
Feature Comparison
Core Email Features
| Feature | EmailEngine | Unipile |
|---|---|---|
| IMAP/SMTP | Yes | Yes |
| Gmail API | Yes | Yes (OAuth2) |
| Outlook/Exchange | Yes | Yes (OAuth2) |
| OAuth2 | Yes | Yes |
| Webhooks | Yes | Yes |
| Send emails | Yes | Yes |
| Attachments | Yes | Yes |
| Search | Yes (IMAP search) | Yes |
| Labels/Tags | Yes | Yes |
| Threading | Partial (Gmail/MS Graph/Yahoo) | Yes |
| Bounce Detection | Yes | No |
| Mail Merge | Yes | No |
| Templates | Yes (server-side) | No |
Beyond Email
| Feature | EmailEngine | Unipile |
|---|---|---|
| LinkedIn Messaging | No | Yes (full integration) |
| No | Yes | |
| Instagram DM | No | Yes |
| Facebook Messenger | No | Yes |
| Calendar Sync | No | Yes (Google/Outlook) |
| Meeting Scheduling | No | Yes |
Integration Features
| Feature | EmailEngine | Unipile |
|---|---|---|
| REST API | Yes | Yes (500+ endpoints) |
| Webhooks | Yes | Yes |
| Webhook retry | Yes | Yes |
| Batch operations | Yes (mail merge, bulk updates) | Limited |
| Rate limiting | Configure yourself | No Unipile limits (provider limits apply) |
| SDKs | Community | Official (Node.js, PHP) |
Pricing Deep Dive
EmailEngine Pricing
Structure:
- Annual license: See postalsys.com/plans for current pricing
- Unlimited mailboxes
- Unlimited API calls
- Unlimited instances
Your costs:
| Cost Component | Amount |
|---|---|
| EmailEngine License | Flat annual fee (see pricing) |
| Infrastructure | Variable (VPS/cloud) |
| DevOps Time | Variable |
Cost scales with infrastructure, not mailbox count.
Unipile Pricing
Pricing as of 9 December 2025
Pricing may change. Check unipile.com/pricing-api for current rates.
Structure: Per connected account per month with volume discounts.
Pricing Tiers:
| Connected Accounts | EUR/Account/Month | USD/Account/Month (approx.) |
|---|---|---|
| Up to 10 | 49 EUR flat total | ~$55 flat total |
| 11-50 | 5.00 EUR | ~$5.50 |
| 51-200 | 4.50 EUR | ~$5.00 |
| 201-1,000 | 4.00 EUR | ~$4.50 |
| 1,001-5,000 | 3.50 EUR | ~$4.00 |
| 5,001+ | 3.00 EUR | ~$3.50 |
What's Included (All Tiers):
- All features (Email, LinkedIn, WhatsApp, Calendar, etc.)
- Unlimited API calls
- Real-time webhooks
- Official SDKs
- No commitment required
Free Trial:
- 7 days
- All features included
- No credit card required
Cost scales with connected account count.
Choose Unipile if:
- You need multi-channel messaging (LinkedIn, WhatsApp, etc.)
- You want EU-hosted data (GDPR compliance)
- You don't need to self-host
- You're building a CRM, ATS, or sales outreach tool
Choose EmailEngine if:
- You only need email integration
- You want to self-host for maximum control
- You have many mailboxes and want predictable flat pricing
- Data must stay on your own infrastructure
Operational Considerations
Scaling
| Aspect | EmailEngine | Unipile |
|---|---|---|
| Vertical Scaling | Increase server resources (CPU, RAM) | Automatic, transparent |
| Horizontal Scaling | NOT SUPPORTED (no built-in coordination) | Automatic, transparent |
| Bottleneck | Usually Redis or network to IMAP servers | Provider API limits |
| Max Scale | Several thousand mailboxes per instance | Unlimited (provider limits apply) |
| Scaling Effort | Manual configuration required | Zero configuration |
Best for:
- EmailEngine: Small to medium scale (under 5,000 mailboxes per instance)
- Unipile: Any scale, especially when multi-channel is needed
Provider Rate Limits
Unipile does not impose its own rate limits, but underlying providers do:
| Provider | Limit |
|---|---|
| Gmail | 500 emails/day (personal), 2,000/day (Workspace) |
| ~100 connection requests/day, ~150 messages/day | |
| ~50 messages/day recommended |
EmailEngine exposes you directly to IMAP server limits, which you must manage yourself.
Data Sovereignty and Compliance
| Aspect | EmailEngine | Unipile |
|---|---|---|
| Data Location | Your infrastructure | EU (France/Scaleway) |
| Encryption Key Control | You control | Unipile controls |
| Data Retention Control | You control | Unipile manages |
| GDPR Compliance | Easier (no third-party) | Yes (EU-hosted) |
| SOC 2 Type II | You must implement | Certified |
| Compliance Implementation | Your responsibility | Professional support |
Best for:
- EmailEngine: Maximum data control, no third-party data storage
- Unipile: EU data residency requirements with managed compliance
Use Case Recommendations
Choose EmailEngine If:
- You only need email
- No LinkedIn, WhatsApp, or calendar requirements
- Deep email protocol features needed (bounce detection, mail merge)
- Email-focused application
- Data sovereignty is critical
- Banking, healthcare, legal
- Government contracts
- Data must never leave your infrastructure
- Cost is a major factor
- High mailbox count (500+)
- Predictable flat pricing needed
- No per-account fees
- You want source-available code
- Want to audit and inspect code
- Source code available for review
Choose Unipile If:
- You need multi-channel messaging
- LinkedIn outreach automation
- WhatsApp business messaging
- Unified inbox across channels
- You're building a CRM or ATS
- Sales outreach tools
- Recruiting platforms
- Customer communication hubs
- Zero DevOps overhead desired
- No infrastructure to manage
- Small team focused on product
- Want fully managed solution
- EU data residency is sufficient
- GDPR compliance needed
- EU-based data hosting acceptable
- SOC 2 Type II certification required
Bottom Line
EmailEngine is best for:
- Email-only applications
- Self-hosted requirements
- Cost-sensitive deployments with many mailboxes
- Maximum data control
Unipile is best for:
- Multi-channel communication (Email + LinkedIn + WhatsApp)
- CRM/ATS/outreach tool development
- EU data residency with managed compliance
- Zero-ops preference
Key difference: EmailEngine is email-focused and self-hosted; Unipile is multi-channel and cloud-only. If you only need email and want full control, choose EmailEngine. If you need LinkedIn, WhatsApp, and other channels with managed hosting, choose Unipile.