Category: Email
Read time: 8 min read
Google and Microsoft tightened sender rules. Here's how to set up domains, inboxes and warmup so cold email lands in the inbox.
Cold email in 2026 needs dedicated sending domains separate from your main domain, multiple warmed inboxes, correct SPF, DKIM (2048-bit) and DMARC set to quarantine or reject, one-click unsubscribe headers and spam complaints kept under 0.1 percent. Send modest volume per inbox, rotate across many inboxes, vary your copy and monitor placement constantly.
Google and Yahoo introduced bulk sender requirements in 2024 and Microsoft followed. In 2026 enforcement is stricter and based on sending patterns, not just a daily volume number. Authentication, complaint rates and unsubscribe handling now decide whether you reach the inbox.
Buy a few domains that look like your brand, such as variations of your company name, and point their websites to your main site. If a sending domain gets damaged, your main domain and your team's everyday email stay safe.
Every sending domain needs three records set correctly.
Create several inboxes per domain and warm each one for about two weeks before real campaigns. Warmup builds a positive sending history so providers trust the inbox.
This is why serious programs spread volume across many inboxes. RGI Systems, for example, runs client email across roughly 80 managed inboxes so each one sends at a safe level while the program reaches up to 15,000 emails a month.
Spam complaints are the fastest way to lose deliverability. Aim for under 0.1 percent. Between 0.1 and 0.3 percent you can see filtering, and above that throttling or blocking becomes likely.
The best protection is relevance. Tight targeting, messages that reference something real about the prospect, and an easy way to opt out keep complaints down.
Short, plain-text emails with one clear ask perform best. Use several variants of each step so providers don't see thousands of identical messages, avoid heavy links and images early in a sequence, and stop the sequence as soon as someone replies.
Track bounce rate, reply rate, complaint signals and inbox placement by domain. Rest or replace any inbox that starts to slip. Deliverability isn't a setup task. It's ongoing maintenance.