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.

Set up automatic warm-up

Recommended warm-up settings

Warm-up during campaigns

To ensure your cold emails reach the inbox, warm up email accounts before launching outreach campaigns.

Email warm-up gradually increases sending volume and builds your sender reputation through positive signals like opens and replies.

Why you need warm-up

• Prepare your sending accounts for campaigns

• Build sender reputation through automated sending

• Improve deliverability and avoid spam filters

Set up automatic warm-up

Warm up your accounts through Snovio's 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.

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

Recommended warm-up settings

Add your email accounts to automatic warm-up. Here are the settings we recommend for best results.

Warm-up period

A warm-up should be long enough to see a real effect. If you start sending too early, you can lose the progress from the warm-up or make it take longer to reach good deliverability.

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

Never launch campaigns without warm-up. Warm up every sender account properly before any campaign.

Warm-up strategy:

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

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.

Warm-up pool:

Turn on the Premium sender pool in Snovio to warm up your account using business email addresses.

Choose the providers you want to use for provider-specific warm-up. This way, your warm-up emails are sent to the same providers, which helps improve deliverability with providers like Gmail and Outlook.

Warm-up statistics

Monitor Deliverability score on the warm-up dashboard to decide whether to extend or adjust your warm-up. If inbox score is lower than 80% → extend warm-up until the score improves.

If deliverability shows bad results during warm-up, decide the best approach based on your account:

• New mailbox:

If it's a new account with little to no sending history, continue the warm-up. If you stop it before completing a 4 week warm-up, it may impact your sender reputation. Check your mailbox health with the deliverability tests and review DNS records.

• Existing mailbox:

If your email account is already active and is used to send campaigns, don’t pause warm-up. Check your mailbox health with the deliverability tests, review DNS records, and reduce email sending limits while warm-up continues.

Deliverability checks during warm-up

Simulation sending is a must for every stage of your outreach. You can do it with Snovio’s all-in-one checker Deliverability Check.

Run deliverability tests and decide if your account is ready based on its results.

Test frequency

• After warm-up (Before launching any campaign)
• At least once a week while campaigns are active
• Every time before you increase the sending limit

Metrics to monitor

Check these results after running tests:

Domain health

75% is the minimum acceptable score to start campaigns; 100% score is recommended before you increase sending limits.

Inbox placement

90% inbox across target providers (Gmail/Outlook): the sender can be used.

80% inbox: fix any underlying issues. Rebalance more volume from campaigns into warm-up

Spam rate

5% or more spam: Don’t use this sender for campaign → run on the warm-up only

Use Warm-up during campaigns

When you start outreach, don’t use your full daily limit for campaigns only.

Always keep part of account's limit for warm-up. Your daily sending limit should be split between cold emails and warm-up emails to protect deliverability.

Warm-up and campaign sending limits

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

For your first campaign after warm-up, Snovio recommends these limits:

• 40 warm-up emails/day

• 10 campaign emails/day

Warm-up and campaign sending limits are set separately in the settings, but they both count toward your total daily limit per email account.

- Set the warm-up limit in the warm-up settings

- Set the campaign sending limit in your email account settings

If deliverability stays above 90%, gradually shift limit from warm-up to campaign:

• Each week, add 5 emails/day to campaign sending

For your active campaign sending phase, Snovio recommends these limits for campaigns and warm-up:

• 30 campaign emails/day

• 20 warm-up emails/day

• If you notice deliverability issues, reduce campaign sending and increase warm-up

Deliverability protection

Your sender reputation changes based on your email activity. Cold outreach can bring negative signals, like bounces or spam reports. Warm-up helps keep steady activity and adds positive signals.

Keep warm-up running when you’re not sending campaigns. Long breaks in sending can hurt your reputation, and you may need to warm up again before your next campaign.

Use warm-up as a background process to protect deliverability — not just a one-time step.

• Keep warm-up active during campaigns and between campaigns

• Avoid long gaps in sending

• When campaigns are active, split your daily limit between campaign and warm-up

• When campaigns are paused, use your full daily limit for warm-up

• On days when you send fewer emails than usual, add warm-up emails to keep activity steady

Mailbox rotation

Warm up more mailboxes to always have additional senders in your back-up. When you need to reach more prospects, add warmed-up senders from your back-up pool, not completely new accounts.

Use mailbox rotation to increase your total limits safely. Add as many accounts as your need to hit your sending goal. Every mailbox in rotation should use the recommended limits.

Review performance for each mailbox in the Reports dashboard.

Related articles:

Email Warm-up: tips and recommended warm-up settings

Warm-up slots and sending limits in Snovio plans