Email Warm-Up best practices: How to get the best results

This article shares essential tips and best practices to help you get the most out of email warm-up and use it effectively.

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Properly warmed-up email accounts provide a solid foundation for a successful cold email campaign.

The warm-up strengthens your sender reputation and improves the ability of your emails to land in the Inbox. Doing it right requires a smart approach and sticking to best practices.

Let's dig into some key things to do and avoid for important warm-up aspects:

Warm-up period

The first recommendation is simple—don't send campaigns without the initial warm-up period. Consider it as preparation before going live; never underestimate its importance.

The warm-up's duration depends on your email account's age and condition:

at least 4 weeks for newly created mailboxes;
at least 2 weeks for older accounts with some sending history.

To do: Complete a warm-up period before sending any campaigns or cold emails. It helps your email account get in shape for real campaigns.

Keep in mind that launching an email campaign before completing the warm-up can set back its progress. Wondering why?

This is because warm-up generates only positive interactions, and real campaigns sometimes bring in the negatives (bounces, spam reports) which can reduce the positive effect gained during warm-up.

Warm-up limit (daily warm-up emails)

The warm-up process helps your account reach the desired sending limit safely. If your plan is to send 50 emails per day in campaigns, reach this limit through a warm-up first.

Avoid this mistake: Don’t start warm-up with a high limit on day one. Remember, emails sent for warm-up count as real emails.

For best results, it's important to set account limits based on whether the account is used for sending or is new.

Active accounts (already sending campaigns):

If the account is already sending campaigns, make sure the total volume (campaign + warm-up) stays within the safe recommended limit.

Balance the number of emails sent in campaigns and in warm-up. The combined sending limit should not exceed 50 emails/day. For example:

Campaign 40 emails/day → Warm-up 10/day
Campaign 25 emails/day → Warm-up 25/day

New or inactive accounts (no active campaigns):

For accounts you just created or the ones that haven't been used, start warm-up with a low limit.

Enable Progressive strategy in the settings to start with a lower limit and reach your target gradually.

The recommended default settings for the Progressive warm-up:

Starting volume: 2
Daily volume increase: 2
Daily sending goal: 40

We recommend a daily warm-up goal of up to 40 emails/day, which is a safe limit for your account’s reputation.

Email account activity

Your sender reputation grows from consistent email-sending activity and positive engagement.

If you leave your account inactive for some time or reduce sending activity, its reputation might go down a bit. This is because email providers re-evaluate your account and might treat it as "new." In this case, you'll need to warm it up again.

To do: Keep your account "busy" with a warm-up when you don't send any campaigns. A period of inactivity can cause your account to lose its "heat." When your email campaign is completed, start a warm-up to maintain activity.

Remember: Avoid sudden changes in sending volume, like sending zero emails one day and 100 the next — email providers may view this as suspicious activity. Consistency in email activity (roughly the same number of emails every day) is good for the reputation.

On days when you don't run any campaigns or send fewer emails than usual, add in some warm-up emails to maintain steady activity.

Set your warm-up schedule to match your usual email-sending times: this helps align with what is considered the "usual behavior" for your email account.

This way, your email account will maintain its strength and sender reputation during periods of inactivity as you prepare for your next campaign.

Email sending volumes

One of the key settings for your campaigns is the sending limit (Messages per day). You can edit this parameter in your email account settings.

Aspect #1: The starting limit after a warm-up period

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

Aspect #2: Balancing cold emails and warm-up emails

Using your entire limit for campaigns with no warm-up is not recommended, even if results look good.

To keep your sender reputation stable, avoid using your full daily limit for campaigns alone. It’s best to reserve part of your volume for warm-up to support deliverability.

When sending campaigns, your daily sending volume should be split between cold emails and warm-up emails.

The recommended ongoing split between campaign and warm-up is:

30 campaign emails
20 warm-up emails

A 50/50 split (25 campaign / 25 warm-up) can be acceptable when deliverability remains stable and the engagement is strong.

Aspect #3: Using warm-up during email campaigns

Your sender reputation continues to change while campaigns are active. Cold outreach can generate negative signals such as bounces, spam reports, or lower engagement, which may affect deliverability over time.

Keeping warm-up active during campaigns is always recommended. Active warm-up helps protect deliverability and prevents reputation drops.

Warm-up emails generate positive engagement signals that help offset potential negatives from real campaigns and keep your reputation stable.

To do: Always reserve part of your daily sending limit for warm-up, even when campaign results look good.

Warm-up should be treated as an ongoing background process that supports inbox placement throughout your outreach — not just a one-time setup step.

Warm-up email content

In Email content settings, choose between the options depending on your warm-up goal.

Specific template

You can add your own email template that you plan to use in real campaigns. Warm-up will use this exact template to improve deliverability.

Because the same content is used, keep the daily warm-up limit lower—around 5–10 emails per day.

Repetitive content can look suspicious. To make the warm-up less repetitive, use Spintax.

You can insert spintaxes from the Variable menu in the Email content settings (it's available only in Specific content type).

Tip: Spintax adds variation that helps both cold emails and warm-up. For best results, use meaningful variations. Random simple phrases may not be effective and can even harm the warm-up progress.

Bad Spintax uses

{Hi|Hey|Hello} — a simple change in the greeting will have little to no impact.

{Thanks|Thanks a lot} — micro-variations will have no effect.

I {want|would like} to talk — a rephrase that doesn’t change the sentence at all.

We {accelerate|turbocharge|10x} growth — adding hype synonyms to Spintax increases the risk of triggering spam filters.

Good Spintax uses

Openers (different sentence structure, same intent):

{Reaching out|Following up} about {your outbound results|reply rates}.

Noticed you are {hiring AEs|increasing SDRs}—thought this might help.

I work with {teams like|companies similar to} yours on {reply rate|meetings booked}.

Rephrase problem + value:

Recently helped {Acme|Company} {double meetings|reduce bounces by 35%}.

Seeing {low reply rates|slow pipeline} from cold emails? We help teams {improve replies by 20–30%|book more first meetings} by {clarifying ICP + cleaning data|fixing list quality + email copy}.

CTA:

{Happy to share a 2-min breakdown of what worked |Are you open for a quick run-down?}

If not the right fit, mind pointing me to {the right person|who does outbound}?

AI-generated emails

This option is best suited for the first warm-up of a new account or for restoring reputation after a period of inactivity.

AI-generated warm-up emails have unique content to avoid repetitiveness. To make them look less generic, we add manually pre-written subject lines and phrases.

AI-generated emails use plain text mode by default to improve warm-up effectiveness. If you add a custom tracking domain to warm-up, plain text mode will be disabled automatically because adding a link turns the email into HTML.