Complete Guide to Email Warmup 2025: Improve Your Deliverability

The email warmup has become essential for any successful sales prospecting in 2025. Before launching your first campaigns, this preliminary step is essential to avoid spam and maximize your results. In this complete guide, discover why and how to succeed in your email warmup step by step.

Spam filters have become ultra-sophisticated. In 2025, even a perfectly written email can end up directly in spam if it comes from an address with no history. With an average deliverability rate of only 83% worldwide, you can no longer skip this crucial step.

Warming up is the process of gradually building your email reputation with providers like Gmail or Outlook. It’s like building your credibility step by step, showing that you’re a reliable sender who sends relevant content.

Experience has shown us that an effective warm-up requires at least 15 days, with a gradual and controlled increase in load. Here is the schedule that we recommend at Akidel:

• The first few days are crucial.
  Start small with just 10 emails on the first day. This is the time to build your reputation. Focus on sending to trusted contacts who will engage with your emails.
• Then gradually increase:
  15 emails on day 2, 20 on day 3, 25 on day 4… This constant but measured progression allows email providers to see that your activity is natural and legitimate.
• Around the middle of the process (days 7-8) you will reach 40-45 daily emails.
  This is a pivotal phase where you need to pay particular attention to your deliverability metrics.
• The last week allows you to gradually reach 100 daily emails, which represents an optimal volume for most B2B campaigns.

Essential manual actions during email warmup

Automation makes the process easier, but some manual actions remain essential for a successful warmup:

Check and optimize your technical configuration.
SPF, DKIM, and DMARC records must be properly configured before you begin. These are the foundation of your sender reputation.

Create authentic interactions. Really engage with your contacts, don’t just rely on automated sending. Reply to emails, forward some, mark others as important. These manual actions have a major impact on your reputation.

Monitor your deliverability metrics daily. A good warmup results in open rates above 25% and consistent placement in the primary inbox.

How Akidel supports you in this process

Our platform combines intelligent automation and manual control to optimize your warmup:

• The system automatically manages the gradual increase in load according to the optimal 15-day schedule. You don't have to worry about the number of emails to send each day.
• A clear dashboard allows you to track your essential metrics in real time: deliverability rate, inbox placement, engagement rate.

Common mistakes to absolutely avoid

Don't rush things. The temptation is strong to rush the process, but that's the best way to ruin your sender reputation. Stick to the recommended progression.

Diversify your interactions. Don't always send the same type of content at the same times. Vary your messages and sending times to appear more natural.

Don’t neglect tracking. Even with automation, you need to stay on top of your metrics. A sudden drop in open rates or an increase in spam should be a red flag.

Maintaining your reputation after the warmup

Warmup is just the beginning. To maintain good deliverability over the long term:

• Keep sending volume stable. Avoid sudden spikes that can trigger spam filters. The recommended limit is 100 daily emails via SMTP.
• Continue to generate engagement. Even in the prospecting phase, your emails must generate regular interactions to maintain your reputation.
• Clean your contact list regularly. Inactive or bouncing addresses can harm your reputation.

Ready to start your warmup?

The warmup email has become an essential step in 2025 for any serious company in its B2B prospecting approach. By following this guide and using the right tools, you will maximize your chances of success.

FAQ – Your questions on the warmup email

How long exactly does a warmup last?

The minimum is 15 days to establish a baseline reputation. In some cases, especially for new domains, a longer warmup may be necessary. The important thing is to achieve stable metrics before launching your campaigns.

Should I do a warmup for each new email address?

Yes, absolutely. Even if you use the same domain, each new address must go through its own warmup process. This is an essential step that we automate at Akidel.

How do I know if my warmup is working well?

Monitor three key metrics: your deliverability rate (must be >90%), your open rate (aim for >35%), and your inbox placement. Our dashboard gives you access to all these indicators in real time.

Can I send prospecting emails during the warmup?

We strongly advise against this for the first two weeks. Focus on building your reputation first before starting your prospecting campaigns.