Email Verification Infrastructure
SPS Verify operates a small, dedicated fleet of SMTP-handshake verification nodes. We validate email addresses on opt-in lead lists for outreach hygiene — keeping bounce rates low and sender reputation healthy.
What we do
Each address on a list is checked via a lightweight SMTP handshake. We confirm the recipient domain accepts mail (MX), the address resolves at the destination server (RCPT TO), and the address isn't a catch-all or role account. We don't send marketing or bulk email — only the protocol-level validation step.
This is standard deliverability hygiene. ESPs require clean lists; senders with high bounce rates get filtered. Running our own dedicated infrastructure rather than outsourcing to a third-party API gives us better control over verification quality, latency, and cost at the volumes we operate.
Verification fleet
Five nodes serving SMTP verification requests, distributed across the fleet for capacity and reliability.
mx1.spsverify.com
Operationalmx2.spsverify.com
Operationalmx3.spsverify.com
Operationalmx4.spsverify.com
Operationalmx5.spsverify.com
OperationalOperational practices
SPS Verify runs within standard ESP and ISP guidelines:
- Verifies only addresses on opt-in lists with a legitimate basis to contact
- Uses SMTP handshake validation only — no sending, no marketing email from these nodes
- Honors receiver-side rate limits and backs off when servers signal pressure
- Maintains reverse DNS, SPF alignment, and FCrDNS on every verification IP
- Operates dedicated, bounded-rate nodes — not anonymized open relays