If once in your life, you told yourself stuff like:

Holly Shit! My open rate is way too low!


Why the hell are my emails going to Spam?!

...then keep reading!

โš ๏ธ NOTE: This article might contain some explicit language. I'll try to avoid using such language as much as possible in order to keep my classy frenchmen reputation. ๐Ÿฅ–๐Ÿ‡ซ๐Ÿ‡ท But also to make my mum proud! ๐Ÿ˜‡

Now that you've been warned, let's get right to it!

We all know that sending cold emails is still one of the most efficient ways to acquire customers in B2B. Yet, according to Return Path, 21% of opt-in emails never end up in the person's inbox.

I know, pretty frustrating!

In this article, we'll dive into how to warm up your email account and keep it that way, so you make sure to have the perfect email deliverability.

You'll see some of the best ways to take care of your email reputation, set up SPF and DKIM records, but also learn what profile settings need your attention.

If you didn't understand a single word of the previous 2 sentences, it's ok. I'll explain everything in a minute! ๐Ÿ˜˜

Sometimes, for no reason whatsoever, a new email address you've set before sending your cold emails can get penalized.

We're talking about being blocked and having to deal with a low open and email deliverability rates. Even if you did everything right from the start! ๐Ÿ˜ณ

Not fair, you say?

I agree!

Here are a few things we'll go through in this article, so that you never have to experience this grave injustice.

Should you use a different domain for your email outreach?

When starting with email outreach, you might stumble upon a lot of so-called "experts" that tell you to do things that they've never really tested.

At lemlist, we've analyzed more than 10,000 email accounts who've sent over 20 million emails. During the process, we've defined 3 clear patterns when it comes to which domain people tend to use for email outreach.

1- You've just bought your domain, launched a new website and now want to email people massively

Huge chance your email address hasn't been warmed up yet. That means there's a super high risk of getting blocked if you try to email thousands of prospects at the same time.

So, what should you do?

๐Ÿ‘‰ You can buy another domain for your email outreach.

If your current domain is mycompany.com, you could use mycompany.co for your email outreach for example. This will allow you to protect your domain in case you get blacklisted or marked as spam.

The issue is that using another domain might also send fake signals to your audience. It also requires more work to set it up properly.

๐Ÿ‘‰ Personalize your messaging as much as possible

Do all the steps in this detailed guide and therefore, keep your existing domain to do the email outreach.

That's actually what we did at lemlist and our campaigns, with 0% bragging of course, are pretty successful. ๐Ÿ˜‡

Cold Email Results

You can read more about how I booked 44 meetings at SaaStr conference with one ultra personalized cold email campaign.

2- You're a fast-growing startup with a "large" sales team

If you're a fast-growing company, it means by definition that the amount of emails your domain is sending will increase heavily.

In this case, you are onboarding more and more salespeople who will get new and not properly warmed up email accounts.

The risk if you're using your own domain?

To get blacklisted very quickly and see a decrease in deliverability for all your emails.

Including transactional ones!!! (It means your onboarding and billing will go to spam ๐Ÿ˜ข)

๐Ÿ‘‰ I would highly recommend to use another domain for outreach, and take the time to go through all the steps mentioned below.

I know for a fact that when you're scaling outbound, you want to scale the number of emails you send as quickly as possible. But sometimes, it's worth to spend more time building a strong domain reputation because it will pay off in the long run.

3- You're an established company that has been around for years, with an excellent domain reputation

If you've been around for a few years already and you've been sending a decent amount of emails, this usually means that your domain reputation is good. In my opinion, you should leverage it as your strength.

When sending cold emails, the risk of getting blacklisted or marked as a spammer is very low if you're doing things the right way.

Personalizing your message is always a good idea because it will maximize the number of replies and meetings booked.

As an example, Zendesk is using lemlist with the main zendesk.com for their email outreach. Their campaigns are also pretty successful.

Results are amazing:

Zendesk cold email results

Now that we've mention "domain reputation" a few times, let's have a look at what it really means...

What is domain reputation and how do you maintain a good one?

A domain reputation is exactly what it says to be.

You can see it as the swag of your domain. If you've been acting cool - you're good. You can "get in" the inbox of the people you'll be messaging.

If not...

You'll get denied and your emails will end up in spam. ๐Ÿ˜ฉ

How do you make sure your domain is part of the cool kids?

For starters, try to obey a few simple rules:

What's the hell is domain authentication?

In order to continue with analogies, domain authentication can be seen as the ID of your domain.

This helps algorithms know that you're a real human being and that you're legit.

A bit like when you try to enter a club in high school.

No ID?


So, how can you set up your email ID to make sure you have the coolest domain reputation ever? ๐Ÿคฉ

Let's have a look at the SPF and DKIM!

How to authenticate your domain with your SPF and DKIM?

Domain authentication is a critical component of any email strategy.

When an email provider performs an โ€œID checkโ€, they want to verify that the email is actually coming from you and not somebody else.

This is the way the internet fights spammers.

There are two main ways to set up email authentication: SPF and DKIM.

  • SPF (Sender Policy Framework) is an email validation system designed to prevent spam by verifying the senderโ€™s IP address.
  • DKIM (DomainKeys Identified Mail) indicates ownership of the email message by a particular organization.

Go to mailbox checker and put your domain to check your current SPF and DKIM settings.

SPF and DKIM checker

If you have some problems with SPF or DKIM, you need to set it up ASAP. Here are the guides if you're using G Suite (Google Apps):

For Microsoft Office 365 email account you can use this guide.

A very important point to have in mind is your profile setup.

How to set up your email profile correctly?

Let's take Gmail as an example. You've created your address and you need to fill in the blanks.

Make sure to enter all the necessary information so it looks as complete as the example below. ๐Ÿ‘‡

Don't be lazy, it literally takes one minute to set it up. Then your profile will look like the real human being you are. ๐Ÿ˜

email deliverability

Now, that you know when my birthday is, I really hope to receive a lot of gifts on the 9th of June. ๐Ÿ˜‡

But that's not the topic!

Your account looks like one of a pro. Time to learn how to warm it up!

How to warm up an email domain and keep it warm?

This is the section you've been waiting for. Therefore, let's start from the top.

What is email warm-up?

Email warm-up is a process that involves gradual increase of your sending volume. A warmed-up email address is one that has been sending and receiving messages as a real person would, when creating their email.

An email address can be at a different stage depending on how you've been using your account.

Remember when we discussed domain reputation?

In order to build a good reputation, your email address needs to be warmed up.

But, how does the email warm-up process look like? What's the best warm-up schedule? How will we know when an email address has been properly warmed-up?

There are actually two ways to do it.

Manual email warm-up process

This one comes down to you sending emails to your friends and acquaintances manually, one by one.

That being said, you should also ask your friends to send you emails and then reply.

Ideally, you'll gradually increase this number if you want to send them at scale.

Manual warm-up schedule:

  • Week 1: between 10 to 20 emails per day
  • Week 2: between 20 to 40 emails per day
  • Week 3: between 40 to 80 emails per day
  • Week 4: between 80 to 100 emails per day

Obviously, the numbers may vary depending on who you're emailing and what does your complaint rate look like.

The big drawback of this method is that it's time-consuming. You also have no insurances that the people you email will reply.

Precisely the reason why we've created a second way!

[#lemwarm] Automatic email warm-up service

This approach allows you to relax while your email address gets warmed up automatically. ๐Ÿฅถ -> ๐Ÿ˜

It all starts with our users. The good thing with lemlist community is that it's the biggest online community around sales automation ๐Ÿค–

Hence, people often face similar problems and are always happy to help each other.

Email outreach community

This is how we've built lemwarm, a feature that allows you to send and receive emails from other lemlisters. Yeah, that's how we call our awesome users. ๐Ÿ˜Ž

In other words, you'll warm up your email account automatically and keep it that way.

Essentially, since your account is connected to lemlist, we'll send emails to other lemlisters using your account with some uniquely generated content. Each message and subject is unique and generated via our smart content algorithm.

Since other people who are sending emails also have their account connected to lemlist, we'll create conversations by replying to those messages with more unique content.

How do you set up lemwarm?

There are three steps:

  1. Go to lemlist and create an account;
  2. Go to settings -> email warm up
  3. Set up your lemwarm and click "Start" button
How to warm up email domain - lemwarm

As a result, we will automatically warm up your domain, without you lifting a finger.

A word of advice...

IF your email account is young (6 months or less):

  1. Number of warm-up emails per day after ramp-up is 30
  2. Ramp-up increment value per day is 1

IF your email account is old (more than 6 months):

  1. Number of warm-up emails per day after ramp-up is 40
  2. Ramp-up increment value per day is 2

Once you've done that, you should go to your email account and set up some rules. For example, as soon as you receive emails from lemwarm, they're automatically archived. By doing so, you won't be mixing them with other emails.


With these filters, you're telling Google that these emails are important to you. Hence, they should never go to spam which makes it an even bigger sign to get the best domain reputation possible.

How long it will take to warm up your email with lemwarm?

The optimal time is one month. After 30 days, your email will be properly warmed up and ready to roll.

In case you want to send emails during the warm-up process, we strongly suggest you to keep your volumes lower (25-50 emails a day during week 1, 50-100 emails during week 2, etc.) and increase gradually week after week. Afterward, you can go all in.

If you're already a lemlister, my advise is to keep lemwarm always active so you're sure your email address stays warm. ๐Ÿ”ฅ

If you're not, then here it comes...

lemwarm is included in all packages, and it will become available after you finish your free trial and become a lemlister officially. ย ๐Ÿ˜Ž

This is it.๐Ÿ‘‡


Now that you know how to warm up your domain and keep it warm, let's have a look at how to make sure your emails end up in your prospect's inbox. ๐Ÿคฉ

How to send emails and maximize deliverability

Email deliverability as a concept is super specific. Real quick, email deliverability is a way to measure whether or not your emails are arriving into prospectsโ€™ inboxes.

It is impacted by many parameters, but these 5 have the biggest impact:

  • Volume & Consistency
  • Complaints
  • Bounce Rate
  • Blacklists
  • Tracking

Let's have a look at those parameters individually and discover the best way to maintain the highest standard.

Volume & Consistency

This means that you shouldn't send a lot of emails out of the blue (or at random intervals). It will negatively impact your domain reputation.

Why? Because itโ€™s what spammers tend to do.

So, if you're doing cold emailing, make sure to gradually increase the number of emails you send.

If you're just starting out, please follow the steps mentioned above to warm up your email address first.

You should use a tool that allows you to spread out the sending of emails so they're not sent as a blast.

A bit like a real human would do! ๐Ÿ˜‡

If you're a lemlister, we do that by default when you define your sending schedule.

You decide the number you want to send per day, during what time frame and our sending algorithm will spread out emails to maximize deliverability.

Cold email scheduler


Thatโ€™s the number of people who put your message in the spam folder.

In order for you to have the lowest complaint rate possible, make sure to keep reading as we will tackle that issue thanks to personalized messaging. ๐Ÿ˜Ž

Bounce Rate

If you're sending emails to addresses that don't exist, your emails will bounce. ๐Ÿ˜ฉ

The higher the bounce rate, the lower your domain reputation.

It's the same as in real life. The more you get rejected from places, the less you'll be able to get in.

In order to keep the lowest bounce rate possible, you should always send to verified email addresses. Make sure to check out my guide on how to find anyone's email address.


If a domain is identified as a โ€œspammer,โ€ ESP (email service providers) will put it on a blacklist.

Thatโ€™s pretty much as bad as it sounds. Obviously, youโ€™ll notice a big decrease in deliverability.

You're probably wondering if you've been blacklisted now. The only way to know that for certain is to test it, for example with Mxtoolbox . ๐Ÿ˜‡

Email Blacklist Checker

When you run the test, one of two things is going to happen:

1) Youโ€™ve got a perfect reputation. Well done, champ. Now you can turn it up a notch. ๐ŸŽ‰

2) Youโ€™ve been blacklisted. Well, crap. Sorry, bud. Getting yourself back in the email providersโ€™ or ISPโ€™s good books is not an easy process. It will take some time, but you can reach out to the companies that have blacklisted you to see if you can be removed from their list of bad domains. ๐Ÿ˜ฑ

For example, if you've been blacklisted by SORBS, you can go through the whitelisted process by following these steps.


Tracking is critical when doing email outreach because it allows you to know if your campaign is performing well or not.

Cold email results (lemlist)

However, tracking click and open rates can sometimes affect the deliverability because the domain used for tracking can be different than the domain you're using to send emails.

In order to avoid this decrease in deliverability, you should always set up your own custom tracking domain.

Custom Domain for cold emails

Setting up your own tracking domain will allow you to increase your deliverability almost instantaneously if you haven't set it up in the first place!

Now that we've went through all the technical aspects on how to maximize the chance of your emails ending up in your prospect's inboxes, it's the perfect time to look at why your messages should be highly personalized!

Why personalization is key when sending your cold emails

Let's face it, when sending cold emails, your end goal is to make more sales.

However, sales is about relationships and attention.

You won't get your prospect's attention by waltzing into their inbox and offering your product or services.

Personalization is what makes a difference between good and average salespeople.

You have all these Social Media networks on every corner. Use it to learn a thing or two about your prospects or companies you wanna partner with.

Do your research. Based on that research, craft your pitch. Make it about them and not about you.

That way, you'll get more replies and less complaints.

With more replies, your deliverability will stay high as you'll be identified as a legit sender.

That's exactly what lemlister (our clients) do. They share their results and templates in cold email templates hub, so you can check their strategies. Like this one:

Cold Email Template that gets replies

If you're looking for templates to build relationships and increase sales, then you need to click here.

I really hope this guide was clear enough for you guys. If not, feel free to ask me anything in the comments.

I would also highly appreciate if you can share it with your community. โค๏ธ

Take care lemlister ๐Ÿ˜Ž