Xsarus
Reliable Email as Crucial
Business Infrastructure
For Xsarus, reliable email delivery is business-critical. 99%+ inbox placement with self-hosted infrastructure built on PostMTA and KumoMTA.
99%+
Inbox Placement
100%
Self-Hosted
0
Third-Party Reliance
Company Profile
About Xsarus
Xsarus provides critical communication services where email delivery is not just important — it is essential to the business. Their platform relies on reliable, timely email delivery for transactional notifications, alerts, and customer communications.
With strict reliability requirements and a commitment to data sovereignty, Xsarus needed an email delivery solution that could deliver enterprise-grade performance while remaining fully self-hosted on their own infrastructure — eliminating dependency on third-party email service providers.
The Challenge
Business-Critical Email Delivery
For Xsarus, email is not a marketing channel — it is core infrastructure. Every delayed or lost message has direct business impact. Their previous solution relied on third-party ESPs, introducing latency, cost, and dependency risks that conflicted with their data sovereignty requirements.
- closeThird-party ESP dependency created latency and cost unpredictability
- closeInconsistent inbox placement rates affecting customer communication reliability
- closeData sovereignty concerns with routing through external providers
- closeLimited control over IP reputation and sending policies
- closeGrowing email volumes making third-party costs unsustainable
The Solution
Fully Self-Hosted with PostMTA
Xsarus deployed PostMTA on their own infrastructure, taking full control of their email delivery pipeline. The self-hosted architecture eliminated third-party dependencies while the KumoMTA-powered engine provided the throughput and reliability their business demanded.
PostMTA's built-in IP warmup automation, DKIM management, and deliverability features gave Xsarus the tools they needed to maintain and grow their sender reputation without manual intervention. Real-time analytics provided full visibility into delivery performance.
Results
The Impact of Self-Hosted Delivery
99%+
Inbox Placement
Consistent deliverability
60%
Cost Reduction
Eliminated ESP fees
100%
Data Control
Full infrastructure ownership
5x
Speed Improvement
Faster delivery times
Deliverability Performance
| Metric | Before (Third-Party) | After (PostMTA) | Improvement |
|---|---|---|---|
| Inbox Placement Rate | ~92% | 99%+ | +7% |
| Delivery Latency | Variable | <1 sec avg | Consistent |
| Monthly ESP Cost | High | Near zero | 60% savings |
| IP Reputation Control | Limited | Full | Complete control |
| Data Sovereignty | At risk | Guaranteed | Fully self-hosted |
“Email is not optional for our business — it is the backbone of our customer communications. Moving to PostMTA gave us complete control over our delivery infrastructure without sacrificing reliability. Our inbox placement rates improved dramatically, and we no longer worry about third-party dependencies or variable latency.”
CTO
Xsarus
Take Control of Your Email Delivery
Join Xsarus and other enterprises that trust PostMTA for business-critical email delivery. Deploy on your own infrastructure with AI-powered setup in under 30 minutes. Built on KumoMTA for maximum performance and reliability.