If you’re sending cold emails, getting flagged as spam is the fastest way to kill your results—and your sender reputation. Whether you’re a founder, an SDR, or just trying to get responses, you can’t afford to wing it. This guide is for people who want real, practical steps to keep their emails out of spam—especially if you’re using Instantly to run your campaigns.
Let’s cut through the noise and focus on what actually makes a difference.
1. Warm Up Your Domain Before You Send Anything
Let’s start here because it’s the step most people rush—or skip—and then wonder why nothing lands.
What it means:
When you use a new domain (or a domain that hasn’t sent cold emails before), inbox providers like Gmail and Outlook are skeptical. They’re looking for signs you’re a real person, not a spam factory.
How to do it with Instantly:
Instantly offers automated domain warmup. Here’s how to use it:
- Connect your email account in Instantly.
- Turn on the “warmup” feature. This sends and receives low-volume, human-like emails with other accounts.
- Leave it running for at least 2-4 weeks before blasting real campaigns.
- Gradually increase volume—don’t jump from 0 to 500/day.
Pro tip:
Don’t bother with “manual” warmup (sending random emails to friends). It’s slow, obvious, and doesn’t scale.
2. Set Up Proper Authentication (Don’t Skip This)
You wouldn’t open a store without a sign and ID. Don’t send emails without authentication.
What matters: - SPF: Tells inboxes which servers can send emails for your domain. - DKIM: Cryptographically signs your emails so they can’t be faked. - DMARC: Says what to do if SPF/DKIM fail.
How Instantly helps: - Instantly checks your records and alerts you if something’s missing. - You’ll need to add/edit DNS records (SPF, DKIM, DMARC) with your domain provider—painful, but it’s a one-time thing.
What to ignore: - Fancy “deliverability services” that promise to fix this for you. Just follow Instantly’s setup guides and do it yourself. If you skip this, you’re almost guaranteed to hit the spam folder.
3. Clean Your Lists—Religiously
Sending to bad or dead emails tanks your sender reputation fast.
What you should do: - Use a real email verifier (there are plenty out there—NeverBounce, ZeroBounce, etc.). - Instantly integrates with some verifiers, or you can upload a cleaned list. - Remove hard bounces and role-based emails (like sales@ or info@).
What doesn’t work: - Guessing which addresses are “probably good.” - Sending to scraped lists with zero cleaning.
Pro tip:
If you ever see a bounce rate above 3-5%, pause your campaign. Fix your list before sending again.
4. Write Like a Human, Not a Marketer
Spam filters hate “salesy” language, weird formatting, and anything that looks like a mass blast.
What works: - Simple, plain-text emails. - Personalization (first name, company name, something specific). - Short sentences, natural tone.
What to avoid: - ALL CAPS, lots of exclamation points, “free,” “guaranteed,” or desperate sales language. - Huge images or fancy HTML templates. - Links to shady sites, or too many links in general.
How Instantly helps: - Instantly’s personalization features let you auto-insert custom fields. - Preview every email before you send. If it reads like a template, so will the spam filters.
5. Watch Your Sending Volume and Schedule
Blasting 1,000 emails on day one is the fastest way into spam. Inboxes notice sudden spikes.
Best practices: - Start with a low daily volume (20-50 emails per account), then slowly ramp up. - Use Instantly’s scheduling tools to spread sends throughout the day. - Stagger campaigns across multiple inboxes if you need more volume.
Ignore the hype: - More volume ≠ better results. You’re aiming for replies and engagement, not just “delivered” emails.
Pro tip:
Mix in reply tracking and pause campaigns if you see a drop in open or reply rates. Something’s wrong—find out before you burn your domain.
6. Monitor Your Deliverability—Don’t Set and Forget
You need to know if your emails are ACTUALLY hitting inboxes, not just “sent.”
How Instantly can help: - Instantly’s deliverability reports show open rates, reply rates, bounce rates, and spam complaints. - Use seed tests (sending to a set of test inboxes) to check for spam placement. - Look for sudden drops in open rates—they usually mean spam issues.
What to do if you start hitting spam: - Pause campaigns. - Check your recent content and links for spam triggers. - Re-warm your domain if needed (but don’t expect miracles overnight).
What NOT to do: - Keep blasting and hope it fixes itself. It won’t.
7. Respond to Replies and Clean Up Unsubscribes
Engagement is a huge trust signal. Ignored replies or spam complaints hurt you.
Do this: - Reply to real responses, even if it’s just “thanks, not interested.” - Remove unsubscribes and complaints immediately. Instantly can handle this automatically—turn it on.
Don’t bother with: - “Re-engagement” campaigns to dead leads. It rarely helps, often hurts.
8. Don’t Fall for Deliverability “Hacks”
There’s a cottage industry of tricks and “guaranteed inboxing” services. Most are smoke and mirrors.
Ignore: - “Warmup” bots that just send gibberish or spam to themselves. - Weird text obfuscation (like “fr.e.e” or “gu@r@nteed”). - Buying aged domains from sketchy marketplaces.
Stick to: - Consistent sending habits. - Clean lists. - Authentic, personalized emails.
9. Use Multiple Domains and Inboxes—But Don’t Go Overboard
If you’re sending significant volume, spreading out across several domains and inboxes can help. But don’t overdo it.
How to approach: - Each domain needs its own warmup, authentication, and care. - Instantly makes managing multiple inboxes easier, but you still need to monitor each one. - Don’t buy 20 domains and blast from all of them. Quality beats quantity.
When to expand: - Only once your first domain is healthy and you need more volume. - If you’re seeing consistent results and want to scale.
10. Stay Up to Date—But Ignore the Hype
Email deliverability isn’t static. Providers tweak algorithms, and what worked last year might not work now.
Stay sharp by: - Checking Instantly’s documentation and updates—they’ll flag any major changes. - Watching your own metrics, not just “best practices” from random blogs.
But don’t: - Change everything every week. If you’re seeing good inboxing, don’t fix what isn’t broken.
Summary: Keep It Real, Keep It Simple
Most spam issues come from rushing, cutting corners, or chasing shortcuts. Stick to the basics: warm up your domains, authenticate everything, send to clean lists, write like a human, and monitor your results. Use Instantly’s tools to make it easier, but remember—no tool can fix sloppy habits.
Start small, pay attention, and don’t let “growth hacks” distract you. If you keep things simple and iterate based on real results, your emails will land where they’re supposed to—right in the inbox.