Deliverability Guide

Whether you're new to cold email or just want a refresher, this guide walks you through the deliverability basics and shows how Instantly supports you along the way🚀

In simple terms: deliverability is how likely your email is to land in someone's inbox instead of their spam folder.

Every time you send an email, providers like Gmail and Outlook decide how much they trust your account. They look at things like:

The better your habits, the more of your emails land in the inbox.

A brand-new email account has no track record yet. If you send hundreds of cold emails on day one, providers get suspicious – even if everything else is set up right.

The fix: build trust slowly. Start small, then increase your sending over time. This is called warmup.

How to turn on warmup in Instantly

If you want to start sending right away, we offer Pre-warmed accounts that are already warmed up and ready to use in the campaign on day one. Pre-warmed accounts include:

MX, SPF, DKIM, and DMARC are technical records that prove you're really who you say you are – think of them as an ID check for your email. Without them, mailbox providers have no reliable way to confirm your messages are legitimate.

This matters more than ever: since Google and Yahoo's 2024 bulk-sender rules, proper authentication is essentially mandatory. If you're connecting your own Google or Microsoft inbox, this is the single most important technical foundation to get right – skip it, and even a well-warmed, well-behaved mailbox can get rejected or sent straight to spam.

Instantly helps check your authentication after you connect an email account and flags anything that's missing or misconfigured. DFY/Airmail/Pre-warmed Accounts come with MX, SPF, DKIM, and DMARC already set up.

Email providers expect sending activity to be distributed. Using multiple mailboxes helps protect your reputation and lets you scale your outreach more safely.

As a guardrail, keep cold sends modest per mailbox, per day – think a few dozen, not hundreds. Pushing one mailbox past that starts to look automated, no matter how well it's warmed up.

Instantly offers:

Consider sending cold email from a domain other than your primary company domain. If a cold-outreach mailbox or domain ever runs into trouble, this keeps the reputation of your main domain – the one behind your everyday business email – protected.

It's standard practice for anyone sending outreach at scale, and Instantly can help you set up and connect a dedicated sending domain.

Even a perfectly set-up email account can land in spam if you're emailing bad contacts. Avoid sending to:

The cleaner your list, the better your deliverability.

You can verify email addresses right inside Instantly before you launch a campaign. Catching invalid or risky addresses early keeps your bounce rate low and protects your reputation.

Your bounce rate shows how many emails failed to deliver.

We will automatically pause campaigns when the bounce rate exceeds 5% to protect your sender reputation and deliverability. This feature is enabled by default for all users

One-click unsubscribe is exactly what it sounds like: a simple way for someone to opt out of your emails in a single click, no hoops to jump through.

It matters for two reasons: Google and Yahoo now require it for bulk senders, and it's a legal requirement under laws like CAN-SPAM and GDPR – so it's both a deliverability lever and a compliance one.

Instantly makes it easy to add an unsubscribe link to your campaigns, and automatically keeps a suppression list so anyone who opts out is never contacted again.

Your first email should read like one person writing to another – nothing fancy. We recommend:

Tracking pixels and links can make an email look like a mass blast, which is more likely to get filtered.

Also worth avoiding, on the first email especially: spammy words (think “free,” “guarantee,” “act now”), attachments, and image-heavy emails. These are common triggers for spam filters.

You can set this as the default for every campaign:

Whenever you can, send:

This is called provider matching. Many customers see better inbox placement by keeping emails within the same provider.

You can enable Email Service Provider (ESP) Matching for all campaigns in the workspace by following the steps below:

You may come across platforms that claim they can guarantee inbox placement. That's not true – no email platform can honestly promise that.

Gmail, Outlook, and other providers make that call, not any sending tool.

What actually helps: following good habits consistently, and using the right tools to make that easier.

Before launching your next campaign, make sure you've covered the basics:

Deliverability can sound technical, but it doesn't have to be. Instantly brings everything into one place, so you avoid common mistakes and keep your sender reputation strong.

If you're short on time – or simply don't want to manage every step of the outreach process yourself – you can use AI Sales Agent.

Whether you're a solo founder, a small team without a dedicated GTM expert, or a growing sales organization, AI Sales Agent makes it easier to start generating pipeline while following the same deliverability best practices covered in this guide.

Deliverability isn't about secret tricks or complicated settings. It's about building trust with email providers and consistently following good sending habits.

Instantly gives you the tools, automation, and support to make that process simple – so you can spend less time worrying about deliverability and more time starting conversations with your ideal customers.

We're here to help you succeed.

Whether you're just getting started or scaling your outreach, our team is ready to help.