My cold emails keep landing in spam. How do I set up sending so they actually reach an inbox?

The clearest single page on the boring setup nobody explains to a first-time sender: why you buy secondary domains, what SPF, DKIM and DMARC actually do, and a three week warm-up schedule with real numbers rather than vague advice to go slow.

Cold Email in 2026: Domains, Deliverability, Replies

From Unify by Austin Hughes 15 min read

• Warm a mailbox for about three weeks (roughly 5 a day, then 10, then 20) before full volume.
• Cap at 25 emails per mailbox per day, going to 65 only when warranted, and never send cold from your primary company domain.
• Keep reported spam under 0.10 percent (about 3 complaints per 1,000) and never let it hit 0.30 percent.
• The first email captures 58 percent of all replies; average reply rate is 3.43 percent, top 10 percent clear 10.7 percent.

Gmail is the judge, so read the judge's own rules rather than a blog's summary of them. This is where the 0.3 percent spam rate ceiling, the authentication requirements and the one-click unsubscribe rule are written down by the people who enforce them.

Email sender guidelines

From Google Workspace Admin Help 20 min read

• Every sender needs SPF or DKIM; anyone sending 5,000-plus messages a day to Gmail needs SPF, DKIM and DMARC together.
• Keep the spam rate in Postmaster Tools under 0.30 percent, and Google's stated target is below 0.10 percent.
• High-volume senders must support one-click unsubscribe plus a visible unsubscribe link in the body.
• Sending domains and IPs need valid forward and reverse DNS (PTR) records, and mail must move over TLS.

Gives you a number to judge yourself against before you conclude the spam folder is the problem: 3.43 percent average reply rate, 5.5 percent for the top quartile. If you are near that, your deliverability is probably fine and your list is the issue.

Cold Email Benchmark Report 2026: Reply Rates, Deliverability and Trends

From Instantly 20 min read

• Average cold email reply rate is 3.43 percent; the top quartile clears 5.5 percent and the top tier 10.7 percent.
• Step one produces 58 percent of all replies, so the remaining 42 percent is what your follow-ups are worth.
• Under 80 words with a single binary-question CTA outperforms; 4 to 7 touches is the useful sequence length.
• Warm domains over 4 to 6 weeks starting at 5 to 10 a day, and keep bounces under 2 percent.

Deliverability is plumbing, and plumbing is easier to watch than to read. This walks through the setup end to end, secondary domains, authentication records, mailbox warmup and the bounce and complaint thresholds that get you binned.

The Ultimate Guide to Cold Email Deliverability in 2025

On Instantly 16 min