About SiSender: Re-Engineering Cold Outreach
We founded SiSender on a simple observation: modern cold outreach software had become bloated, unreliable, and dangerous to domain reputation. We set out to build an outreach CRM rooted in mathematical pacing and total software control.
Pure Engineering Performance
Built on CodeIgniter 4 and optimized PHP, SiSender eliminates heavy single-page application bloat. Sub-50ms server responses, instantaneous database queries, and lightweight vanilla frontend scripts keep operations swift.
Mathematical Deliverability
We reject "secret AI warmup pools" and fake email generation. SiSender protects delivery through rigorous, auditable sliding rate limiters, RFC header threading, and clean DNS CNAME verification.
The Complete Lifecycle
Cold email is not complete until a meeting is booked and revenue is won. Uniting the sequence engine with an 8-stage pipeline board ensures no warm reply is ever dropped by sales representatives.
Core Architectural Principles
1. Exact Software Representation
Every feature, screen, and capability advertised on this public website exists in our production application code. We do not invent features, exaggerate metrics, or display conceptual illustrations.
2. UK GDPR & Responsible Outbound
We build software exclusively for legitimate B2B business development. We strictly condemn spamming and mandate compliance with PECR, RFC 8058 one-click unsubscribes, and automated opt-out suppression.
3. Transparent Commercial Terms
Predictable pricing based on clear technical quotas — mailboxes, monthly dispatches, and active prospects. No hidden surcharges, no punitive lock-in contracts.
4. United Kingdom Engineering
Headquartered in the United Kingdom, our core engineering team supports enterprise B2B sales development organizations across London, Europe, North America, and globally.