If you're sending cold emails in 2025, this is the stack you need. From domain setup to real-time lead tracking, here's how to build a system that scales without getting flagged.
May 9, 2025
Louis Young
The Complete 2025 Cold Email Infrastructure
Most teams fail because they treat cold outbound like a one-tool job. They spam lists, send unverified emails, and burn domain reputation within weeks.
The best-performing B2B teams run cold email infrastructure the right way. That means proper domain setup, live enrichment, verified contact data, and smart automation.
Below is the exact cold email infrastructure we use for high-volume outbound campaigns across SaaS, agencies, and B2B services.
1. Domain Setup: Done-For-You with Instantly and Hypertide
Deliverability is everything. Most campaigns fail before the first email gets sent because the domain setup was wrong.
Instead of spending days setting up domains manually, use DFY options through:
Instantly: Offers managed inboxes, warmup, and sending infrastructure with auto-rotation and deliverability tracking
Hypertide: Fully manages your outbound domain setup, inbox infrastructure, and compliance to ensure you're sending clean from day one
Both platforms handle the technical setup including SPF, DKIM, DMARC, and inbox warming.
You avoid being flagged as spam, and your cold emails actually land in the inbox.
Bonus tool: Use our free spam checker before sending campaigns to ensure your messaging passes filters.
2. Sending Platform: Instantly
Instantly remains the top choice for scalable sending.
Supports unlimited inbox rotation
Handles warmup, deliverability, and sequences
Tracks open rates, replies, and positive outcomes
Works with DFY domain setups or your own domains
The integration with enrichment and CRM tools makes this the easiest platform to run multi-seat outbound at scale.
3. Lead Sourcing: Clay, Apollo, ListKit
Your sending system is only as good as your list. These are the top platforms to build accurate, targeted lead data:
Clay: Pulls live data based on job postings, tech stack, funding, and dozens of public signals
Apollo.io: Filters leads by title, seniority, industry, revenue, and more
ListKit: Delivers ready-to-use lead lists that are already filtered and enriched
We often use all three depending on the client’s ICP and volume needs.
4. Lead Enrichment: Clay and Findymail
Enrichment is what separates noisy emails from high-converting ones.
Use Clay to fill in firmographics, LinkedIn profiles, technographics, and trigger data
Use Findymail to find and verify email addresses with high accuracy
Stack both to generate fully enriched, deliverable-ready leads
This lets you personalize emails at scale without sacrificing quality.
5. Website Visitor Identification: RB2B and Vector
Not all cold leads start cold. Some have already visited your site or shown interest elsewhere.
RB2B: Identifies anonymous visitors on your site and shows company data
Vector: Tracks off-site research behavior to surface active buyers even before they hit your site
Feed both into Clay to enrich and prioritize outreach.
6. Scoring, Filtering, and Routing: Clay
Clay is where your outbound engine comes together.
All leads get enriched and scored
Scoring is based on behavioral and firmographic fit
Emails are validated using Findymail
Only qualified leads are routed to Instantly or handed to reps via Slack or CRM
The output is a daily stream of verified, high-fit contacts ready for messaging.
7. Feedback Loops and Automation
Once the machine is running, automation keeps it sharp.
Sync closed deals back into Clay to build lookalike audiences
Trigger sequences or retargeting based on on-site activity
Use Zapier to connect Instantly, your CRM, and Clay into one smooth workflow
Every new signal improves your targeting. Every reply refines your playbook.
Final Thoughts
Cold outbound still works, but only when your system is built properly.
The 2025 infrastructure isn't about sending more emails. It's about sending smarter, cleaner, and faster using connected tools and live signals.
Your tech stack matters. Your enrichment matters. Your domain health matters.
Ready to Build a Smarter Go-to-Market System?
If you're serious about scaling outbound, improving pipeline quality, or building a GTM strategy that actually converts… we can help. Our team works with high-growth B2B companies to design and execute custom systems based on your ICP, signals, and sales motion.
Book a meeting with us today and get a free consultation on your outbound or GTM execution plan.
No fluff. No generic playbooks. Just smart strategy that gets results.