Cold Email Setup Guide: Domain, DNS, and Infrastructure (2026)
Before you write a single cold email, you need infrastructure. The domain you send from, the DNS records you configure, and the way you warm up your sending account determine whether your emails reach the inbox or land in spam.
Most guides focus on copywriting and subject lines. This one focuses on the technical foundation that makes everything else possible. Get this wrong and it does not matter how good your email is.
Use a separate domain for outbound
Never send cold emails from your primary business domain. If your outbound gets flagged as spam, it will affect deliverability for all email from that domain, including transactional emails, support replies, and internal communication.
Register a separate domain specifically for outbound. Choose something close to your main domain: if your company is acme.com, use getacme.com, acmehq.com, or tryacme.com. The domain should look legitimate and be clearly associated with your brand.
Register the domain at least 2-3 weeks before you plan to send. New domains have zero reputation, and email providers are suspicious of domains that start sending immediately after registration.
Setting up SPF
SPF (Sender Policy Framework) is a DNS TXT record that tells receiving mail servers which IP addresses are authorized to send email on behalf of your domain. Without SPF, your emails are more likely to be flagged as spoofed.
The record looks like this: v=spf1 include:_spf.google.com ~all (for Google Workspace). Replace the include with your email provider's SPF record. If you use multiple sending services, include all of them.
Only one SPF record is allowed per domain. If you need multiple includes, combine them into a single record. Having multiple SPF records will cause authentication failures.
Setting up DKIM
DKIM (DomainKeys Identified Mail) adds a cryptographic signature to every email you send. The receiving server verifies this signature against a public key stored in your DNS. This proves the email was not modified in transit and that it came from an authorized sender.
Most email providers (Google Workspace, Microsoft 365, etc.) generate the DKIM keys for you. You add the public key as a DNS TXT record, and the provider signs outgoing emails automatically.
DKIM is essential for deliverability. Without it, your emails lack a key authentication signal that email providers use to determine legitimacy.
Setting up DMARC
DMARC (Domain-based Message Authentication, Reporting, and Conformance) ties SPF and DKIM together. It tells receiving servers what to do when an email fails authentication: do nothing (none), send to spam (quarantine), or reject entirely (reject).
Start with a monitoring policy: v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com. This does not block any emails but sends you reports about authentication failures. Review the reports for a few weeks to make sure legitimate emails are passing.
Once you are confident that SPF and DKIM are correctly configured, move to p=quarantine and eventually p=reject. This protects your domain from spoofing and signals to email providers that you take authentication seriously.
Email account setup
Create dedicated email accounts on your outbound domain. Use real-looking addresses: first@domain.com or first.last@domain.com. Avoid generic addresses like sales@ or info@ for cold outreach.
Set up a professional signature with your name, title, company, and a link to your website. Add a profile photo to your email account. These details make your emails look legitimate to both recipients and spam filters.
Create multiple sending accounts if you plan to send at volume. Spreading sends across 3-5 accounts reduces the per-account volume and looks more natural to email providers. Each account should send no more than 30-50 cold emails per day.
Domain and account warm-up
A new domain with new email accounts has zero sending reputation. If you start sending cold emails immediately, most will land in spam. Warm-up is the process of building reputation gradually.
Week 1: Send 5-10 emails per day to contacts who will open and reply. These can be colleagues, friends, or existing contacts. The goal is to generate positive engagement signals. Week 2: Increase to 15-25 per day. Mix in some cold emails to low-risk prospects. Week 3: Increase to 30-40 per day. Monitor bounce rates and spam complaints. Week 4+: Scale to your target volume, typically 30-50 per account per day.
During warm-up, engagement matters more than volume. Open rates above 50% and reply rates above 10% send strong positive signals. If your warm-up emails are not getting engagement, slow down and fix the content before scaling.
Verifying your contact list
Before sending any cold emails, every address in your list must be verified. A single campaign with a high bounce rate can undo weeks of warm-up and damage your domain reputation.
Use real-time SMTP verification to confirm each email is deliverable at the moment you plan to send. emailfinder.dev verifies every email it returns, so if you source your contacts through the API, they are already verified.
If you have an existing list from another source, run it through a verification service before sending. Remove any addresses that are invalid, risky, or associated with catch-all domains. The goal is a bounce rate below 2%.
Sending configuration
Configure your sending tool to respect daily limits per account. Most cold email tools (Instantly, Smartlead, Lemlist) let you set per-account daily caps. Start conservative and increase as your reputation builds.
Set delays between emails. Sending 50 emails in 5 minutes looks automated. Sending 50 emails spread across 8 hours looks human. Most tools support random delays between sends.
Enable tracking carefully. Open tracking uses a pixel that some email providers flag as suspicious. If deliverability is more important than open rate data (it usually is), consider disabling open tracking. Link tracking can also trigger spam filters. Use it sparingly.
Monitoring and maintenance
Once you are sending, monitor three metrics daily: bounce rate (keep below 2%), spam complaint rate (keep below 0.1%), and inbox placement (use tools like GlockApps or Mail Tester to check).
Google Postmaster Tools gives you visibility into how Google sees your domain reputation. Set it up for your outbound domain and check it weekly. If reputation drops, reduce volume immediately and investigate the cause.
Rotate domains periodically. Even with perfect hygiene, cold email domains accumulate negative signals over time. Having 2-3 domains in rotation lets you rest one while the others are active. Plan for domain replacement every 6-12 months.