How to manually warm up an email? A step-by-step guide (2025)

Warming up an email manually is important to avoid the spam folder and ensure your emails reach the right inbox. But in 2025, with stricter spam filters and higher standards for sender reputation, it’s more difficult than ever to do it right. 

Our step-by-step guide will show you exactly how to warm up your email address manually and set a strong foundation for successful outreach!

Key takeaways:

• Start with a small number of emails and gradually increase the volume to build a positive sender reputation.
• Especially focus on generating genuine engagement, like opens and replies, to avoid being flagged by spam filters.
• Do not forget to make consistent monitoring to detect and address any reputation issues as early as possible!

Understanding email warm-up: Why it matters

Email warm-up is the process of gradually increasing the number of emails you send from a new or inactive email address to build a strong sender reputation. It’s essential for successful B2B cold email campaigns. Without it, your emails will likely end up in spam folders, and all your efforts will go to waste. 

Why? Because email providers like Gmail and Outlook don’t trust new senders right away. They need to see consistent, positive engagement like opens and replies, before they let your emails through. If you skip this step and start blasting out emails, you’ll hurt your sender reputation fast, making it nearly impossible to reach your audience. 

So for anyone serious about email outreach, especially in the competitive B2B space, proper warm-up isn’t just a good idea: it’s non-negotiable!

The basics of manual email warm-up

Manual email warm-up is all about gradually building trust with email providers by increasing your sending volume and engagement over time. Unlike automated methods that rely on technology to manage this process for you, manual warm-up puts you in control of every detail, from the number of emails sent daily to the content and recipients. 

While this offers flexibility, it also requires a lot more time and effort. Manual warm-up is ideal for those who want complete control but can be challenging to scale, especially compared to using email warm-up tools that handle everything automatically.

Here are the essential elements of manual email warm-up:

• The sending volume: You will need to start with a small number of emails per day and slowly increase the volume over several weeks. Jumping too quickly can get you flagged by spam filters and damage your sender reputation.
• The email content: Send personalized, relevant emails that are likely to receive positive engagement, like replies or clicks. Generic content won’t cut it; email providers value genuine interactions.
• The general email activity: Don’t forget to monitor your email performance closely. It means that you must track opens, replies, and bounces to really align your strategy with your business needs. 

While manual warm-up gives you hands-on control, it’s only best suited for small-scale campaigns or when you want to manage every detail yourself. For larger operations, automated tools remain way more efficient and reliable.

Step-by-step guide to manually warm up your email

Step 1: Set up proper authentication

Before you even think about sending a single email, you need to set up SPF, DKIM, and DMARC. These are essential for proving to email providers that you’re a legitimate sender. Without them, your emails are more likely to end up in spam folders, no matter how carefully you warm up your account. Here are the details:

• SPF (Sender Policy Framework): This tells email providers which IP addresses are allowed to send emails on behalf of your domain. It’s like a whitelist that prevents spammers from faking your email address.
• DKIM (DomainKeys Identified Mail): DKIM adds a digital signature to your emails, verifying that the message hasn’t been tampered with during transit. 
• DMARC (Domain-based Message Authentication Reporting Conformance): DMARC ties SPF and DKIM together, providing instructions to email providers on what to do if an email fails authentication (e.g., reject, quarantine).

To implement these, you'll need to update your DNS records. If you're not familiar with this process, it’s worth getting some help, because one wrong step can mess things up. 

Step 2: Make sure your recipients' email are valid

Sending emails to invalid addresses is a fast track to being flagged as a spammer. When you send to non-existent or abandoned emails, providers like Google and Microsoft get the message that you don’t know your audience. 

This tanks your sender reputation but also dilutes your engagement rate, which is the last thing you want during warm-up. You always need high engagement to build trust with email providers.

So, before you send anything, clean your email list. Use a reliable email verification tool to remove invalid addresses and focus only on real, active recipients. This simple step can make or break your entire warm-up process.

Step 3: Start with low sending volumes

Ramping up too quickly is a rookie mistake that can ruin your sender reputation before you even get started. Begin with a low number of emails, think 5 to 10 per day. This slow start shows email providers that you’re not a spammer blasting out hundreds of messages out of nowhere. 

Then, gradually increase your volume over the next few weeks. For example, you can go from 10 emails a day in the first week to 20-30 in the second, and so on, until you’re hitting your target volume. This gradual increase helps build trust and ensures you stay out of the spam folder.

Need a more detailed plan? Check out our guide on how many cold emails to send per day for a step-by-step schedule that keeps you on the safe side!

Step 4: Create engaging email content

Sending the right number of emails is important, yes, but what you say in those emails is what really matters. Generic, boring content is a one-way ticket to the spam folder. Your email needs to grab attention and encourage the recipient to engage. 

Here, personalization is key. Use their name, mention something relevant to their business, and keep it short and to the point, and especially avoid sounding like a robot or sending cookie-cutter sales pitches. Focus on the recipient's pain points and how you can help solve them.

Make your subject line intriguing but not clickbait, and your opening line should be strong enough to make them want to keep reading. You can also add a clear call-to-action, like a question or an invitation to connect. 

Here, the goal is to start a conversation, not just push your product. 

Step 5: Engage in two-way communications

Email warm-up is about creating real, two-way conversations. Email providers love to see engagement from both sides: sending and receiving. This is how you prove you’re not just blasting out emails, but actually interacting with your recipients. The more replies you get, the better your sender reputation.

Encourage responses by asking open-ended questions, inviting feedback, or offering valuable insights that prompt a reply. For example, instead of ending with a generic “Let me know your thoughts,” try something like, “What’s your biggest challenge with [specific issue] right now?” This shows you’re genuinely interested in their needs, not just pushing your agenda.

Once you get a reply, respond promptly. Keep the conversation going to build trust and credibility. Even if it’s just a quick acknowledgment, it shows email providers that you’re engaged and your communications are valuable. 

Best practices for manual email warm-up

Dos of manual email warm-up

Consistency and genuine interactions are key if you want to build a strong sender reputation. Don’t know how to do it? Here’s what you need to know:

• Stick to a consistent sending pattern: Send emails regularly, gradually increasing your volume over time. You must avoid big jumps in your daily sending rate at all costs.
• Only engage with legitimate contacts: You need to engage with people who are likely to engage positively, such as colleagues, friends, or industry contacts.
• Take the habit to monitor your metrics, closely: Keep an eye on open rates, reply rates, and bounce rates if you want to be able to adjust your strategy based on these insights.
• Use essentially personalized content: Remember to customize your emails with relevant information (the recipient’s name, company, or specific interests).
• Follow up strategically: Don’t just send one email and forget about it. Send polite follow-ups to non-responders, but space them out appropriately to avoid looking spammy.

Don'ts of manual email warm-up

Avoid these common mistakes if you want to keep your emails out of the spam folder and build a strong sender reputation. Cutting corners here can quickly ruin all your efforts. Here’s what not to do:

• Don’t send to old or invalid email addresses: Clean your list before you start. Sending to outdated or fake addresses leads to bounces, which can damage your sender reputation and get you flagged as a spammer.
• Don’t use overly promotional language: It means that you must avoid using phrases like “Buy now!” or “Limited time offer!” in your subject lines or content, as these trigger spam filters and can make your emails look like junk.
• Don’t increase your sending volume too quickly: Don’t jump from sending a few emails to hundreds overnight if you don’t want to look suspicious to email providers.
• Don’t neglect follow-ups: Sending a single email and then disappearing doesn’t help your reputation. But spamming follow-ups is just as bad, so find a balanced approach.
• Don’t ignore negative signals: High bounce rates, low open rates, and no replies are red flags. If you see these, don’t just keep pushing and remember to adjust your strategy!

Manual vs. automated email warm-up: Pros and cons

Regarding manual and automated approaches, each has its own strengths and weaknesses. Manual warm-up gives you complete control, while automated warm-up saves time and reduces human error. It scales easily and handles large volumes efficiently, but it can be less flexible and comes with a cost. 

Choose based on your needs: control and customization vs. efficiency and scalability.

If you're sending B2B cold emails, you need a professional email service

In 2025, sending B2B cold emails without a professional email warm-up service is a recipe for disaster. Why? Because a poor sender reputation equals poor deliverability. Your emails will end up in spam, not in front of your prospects. 

Professional services like MailReach automate the entire warm-up process, boosting your sender reputation by gradually increasing email volumes and generating real engagement. This means you can focus on closing deals, not worrying about whether your emails are even getting through.

Manual warm-up might work for small-scale campaigns, but it’s not scalable, and you risk making critical errors. MailReach handles everything for you, from automated interactions with real inboxes to continuous monitoring of your reputation. Don’t leave your outreach to chance and start getting real results!

Discover the best email warmup tool for a perfect deliverability