Email Warm-Up: How to improve deliverability before cold outreach

This guide explains how email warm-up improves deliverability and shows how to set it up using Snovio’s recommended settings—both before campaigns and while you’re actively sending.

Set up automatic warm-up -->

Warm-up during campaigns -->

To ensure your cold emails reach the inbox, warm up each sending account before launching outreach campaigns.

Email warm-up gradually increases sending volume while generating positive engagement signals (opens and replies) that build your sender reputation with providers like Gmail and Outlook. Skipping warm-up can hurt deliverability and cause your emails to land in Spam or Promotions.

Why you need warm-up

The main goal of warm-up is to build your sender reputation. A stronger reputation improves deliverability, helping your emails land in the Inbox instead of Spam (or Promotions).

Prepare your sending accounts for campaigns
Build sender reputation through automated sending and engagement
Improve deliverability and prevent issues caused by a low reputation

When to warm up new email accounts:

Right after you connect accounts to Snovio, before starting campaigns

When to warm up existing email accounts:

If you already started sending without warm-up, pause all active campaigns and do the warm-up period first.

After a pause in outreach (the account hasn’t been used in campaigns for some time)
Before increasing sending limits (when you’re planning to scale campaigns)
To fix existing deliverability issues

Start automatic warm-up

Warm up your accounts through Snovio's dedicated Email Warm-up tool.

The automatic warm-up sends emails on your behalf.

Warm-up emails are sent to inboxes inside our warm-up network (not to your leads or contacts). The network includes real inboxes and our pool of managed mailboxes. These inboxes automatically send, receive, open, and reply to warm-up emails to create positive engagement signals for your account.

During the warm-up campaign, your email account automatically sends and receives these warm-up emails, helping improve your sender reputation and deliverability.

Start automatic warm-up

Recommended warm-up settings

Using the right warm-up settings for better deliverability helps build a strong sender reputation and prevent spam issues.

Minimum warm-up period:

A warm-up should be long enough to see a real effect.

2 weeks: reactivate account after a pause; improve the deliverability of accounts with issues
4 weeks: recommended for new domains and new accounts to prepare them for campaigns

Both new and existing email accounts should be warmed up. In the settings, choose an auto warm-up strategy based on your account and goals.

For new accounts, use Progressive warm-up strategy:

Starting volume: This is the number of emails we’ll send on the first day of the warm-up. Snovio recommends starting with 2 emails per day. The maximum starting limit is 5 emails
Daily volume increase: The number of emails added to the limit each day. Set it to 2 emails
Daily sending goal: The maximum daily warm-up volume. Snovio recommends your warm-up goal 40 emails per day

For existing accounts, use a Steady strategy:

Emails per day: Snovio recommends setting this limit to 40 emails. This number cannot be higher than your email account’s Messages per day limit

Advanced warm-up settings:

Enable a premium pool in Snovio (warm-up with business accounts)
Enable provider specific warm-up (with provider matching) to improve performance on certain providers

For a detailed breakdown of the best settings for email warm-up, see the dedicated guide.

Warm-up benchmarks:

Monitor warm-up deliverability metrics to decide whether to extend or adjust your warm-up.

Before you launch campaigns, check the warm-up progress:

Account finished a proper warm-up period
The deliverability score in warm-up metrics is above 90% for all major providers involved
If lower than 80% → extend warm-up until the score improves
Deliverability is consistent by provider (Gmail/Outlook)
If you see issues on any provider, enable provider-specific warm-up

Warm-up during campaigns

Warm-up and campaign limits are set separately in the settings, but they still add up to your total sending volume per account.

When starting campaign after warm-up:

After the warm-up period is complete, Snovio recommends starting with a split of 40 warm-up emails and 10 campaign emails.

Begin campaigns with a starting split. If deliverability remains stable during a week, gradually rebalance the limit toward campaigns until you reach the recommended ongoing split.

Start a new warm-up campaign using a steady strategy
Set warm-up to 40 emails per day
Set campaign sending to 10 emails per day
Gradually shift volume from warm-up to campaign emails

Active campaign & warm-up balance:

After scaling, Snovio recommends splitting your ongoing sending for 30 campaign emails + 20 warm-up emails.

To maximize deliverability, keep your total daily sending (campaign + warm-up) at 50 emails/day or less.

Rebalance campaign vs. warm-up limits

When you start sending to real prospects, don’t use your entire sending limit for cold outreach. Always reserve part of it for warm-up.

Add +5 emails/week from warm-up to campaign emails
Pause increases once you reach 30 campaign emails + 20 warm-up emails and monitor results

Before increasing your campaign volume, review your campaign results. Only add more to campaigns if deliverability looks normal (low bounces, no provider warnings, stable opens/replies). If you notice issues, keep the same volume for a few more days.

If deliverability stays healthy, you can add more limit to campaign emails (while staying under 50 total emails/day)
If results worsen (for example, reply rates drop), lower campaign emails and increase warm-up