How to use Email Warm-up: tips for best results

This article empowers you with essential tips on how to achieve the best warm-up results 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 depletes the positive effect that was gained.

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.

For effective warm-up, we recommend a limit of up to 40-50 emails/day. 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 setting a daily goal of 40 warm-up emails. It's a safe limit for your account's reputation.

You can increase it up to 100 emails per day if needed, but this carries higher risk — your provider may block your account.

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.

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 #2: Balancing cold emails and warm-up emails

Considering the previous point, you may wonder how you should distribute the overall sending limit.

A good practice is to keep a 50/50 balance between cold emails and warm-up emails.

For example, 25 campaign emails and 25 warm-up emails per day per email account.

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 activity steady.

Here's an example of a balanced sending activity:

Day 1: Sent 50 campaign emails — no warm-up needed.
Day 2: Sent 50 campaign emails — no warm-up needed.
Day 3: Sent 25 campaign emails — sent 25 warm-up emails to maintain balance.
Day 4: No campaign emails sent — sent 50 warm-up emails to keep the account active.

This approach keeps your email volume steady and boosts your sender reputation.

Aspect #3: Using warm-up during email campaigns

Your reputation can also be affected during a real campaign. Someone might report your email, some emails may bounce, engagement can fluctuate - all this has an effect on your sender's reputation.

To do: Use warm-up emails to compensate for the negative effects of sending cold emails and restore or maintain your reputation.

There may be a few scenarios on how you can add warm-up to your sending workflow:

1. You're satisfied with your campaign results:

There's no need to warm up at the same time. You can use your total daily sending limit to send campaigns.

2. Engagement rates in campaigns are good:

However, you want to ensure your Inbox rate stays high.

Throw in some warm-up emails to your total limit and increase the balance in favor of cold emails compared to warm-up emails (35 cold/15 warm-up).

3. If you observe that your open/reply rates are decreasing:

Lower the number of cold emails and increase the ratio in favor of warm-up emails (35 warm-up/15 cold or 45 warm-up/5 cold).

The warm-up process will restore your reputation through positive interactions. After a few days, you can begin to increase the volume of cold emails you send.

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

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.