# List health: the numbers that keep your emails out of spam

> Spam complaints, bounces and unsubscribes decide whether your emails reach the inbox. Here are the numbers to watch, and the limits Google sets.

By The Wizel Team · Published 2026-10-01

A great email can still lose most of its sales if it lands in spam. Inbox providers like Gmail and Yahoo decide where your email goes partly by watching how people react to it. Your list's health is the record they read, so it pays to read it yourself first.

## Four numbers to watch

**0.3%** the spam complaint rate Google tells senders never to reach; aim to stay below 0.1%

- Spam complaint rate: the share of recipients who mark your email as spam. It's the most important of the four. Google's sender guidelines ask senders to stay below 0.1% and never reach 0.3%.
- Bounce rate: emails that couldn't be delivered. Hard bounces are dead addresses and should come off your list. A rising bounce rate usually means old or mistyped addresses are getting in.
- Unsubscribe rate: people leaving on purpose. That's healthier than a spam complaint, but a sudden jump after one send tells you something about that audience or that message.
- Engagement: clicks, and opens with caution, over the last 60 to 90 days. Mailing people who never engage pulls your reputation down.

## What pushes these numbers the wrong way

- Sending to people who haven't engaged in months.
- Importing lists people didn't sign up for, or old lists from a previous platform.
- Sudden jumps in volume, like emailing your whole list for the first time in a year.
- Making it hard to unsubscribe. If leaving is difficult, people use the spam button instead.

## How to keep the list healthy

1. Send everyday campaigns to an engaged segment, not to the whole list.
2. Run a sunset flow: one or two last emails to people who haven't engaged for a long time, then stop mailing anyone who still doesn't respond.
3. Remove hard bounces, and addresses that soft bounce again and again.
4. Use double opt-in on signup sources that attract fake or mistyped addresses.
5. Check the four numbers after every big send, not once a quarter.

> Spam complaints are the number to protect. One careless send to a cold list can hurt your inbox placement for weeks.

## Ask your own numbers in Wizel

With Klaviyo connected, ask the Wizel chat:

- “What's my average deliverability rate?”
- “How many spam complaints did I get last month?”
- “Which campaigns have the highest bounce rates?”

## FAQ

### What's a good spam complaint rate?

Below 0.1%. Google's sender guidelines ask senders to keep spam rates under 0.1% and never reach 0.3%, and say rates above 0.1% already hurt inbox delivery.

### Should I delete unengaged subscribers?

Stop mailing them first. Send a short sunset sequence, then suppress anyone who still doesn't respond. Suppressing keeps their history and stops the sends that hurt your reputation.

### Is landing in Gmail's Promotions tab bad?

No. Promotions is the normal place for marketing email in Gmail. Spam is the problem, so watch your complaint rate and engagement.

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Source: Wizel (https://www.wizel.ai/blog/email-list-health-numbers)
Last updated: 2026-10-01