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!

⚠️ 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. 🥖🇫🇷 But also to make my mum proud! 😇

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 way to acquire customers in B2B. Yet, according to return path, 21% of opt-in emails never end up in the person's inbox.

Yeah 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! 😘

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!

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
  • What is domain reputation and how do you maintain a good one
  • How to authenticate your domain with your SPF and DKIM
  • How to set up correctly your email profile
  • How to warm up your email address and keep it warm
  • How to send emails and maximize deliverability
  • Why personalization is key when sending your cold emails

Cool, we have our plan. Let's crack on!

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 persons at the same time.

So, what should you do?

First, you shouldn't try to blast everyone. Focus on emailing the right people and try to personalize your message as much as possible.

Trust me, I've made this mistake in the past. Here are the two options you have:

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.

The second option is to actually do what I stated above. 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. 😇

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 number of email your domain is sending will increase heavily.

Let's face it, it's an issue and we will elaborate why a bit later.

In your specific case, you are on-boarding 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!!!

In that specific case, I would highly recommend to use another domain for your outreach, and take the time to do all the steps we're mentioning 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, that usually means that your domain reputation is high. In my opinion, you should leverage it as your strength.

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

Personalizing your message is always a good idea because this practice 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.

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. 😩

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

For starters, try to obey a few simple rules:

  • Don't be a spammer
  • Always use verified email addresses to keep your bounce rate as low as possible
  • Personalize your emails to maximize the number of replies
  • Don't send emails at blast (we'll have a look at this soon too)
  • Don't send cold emails if you haven't warmed up your email properly
  • Make sure to authenticate your domain
What's the hell is that domain authentication you're talking about?


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? 🤩

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 “ID check”, 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 sender’s IP address.
  • DKIM (DomainKeys Identified Mail) indicates ownership of the email message by a particular organization.

If you’re using G Suite (Google Apps), follow this guide for the DKIM and this tutorial for the SPF.

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

How to set up your email profile correctly

This is all pretty straightforward.

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

Just make sure to enter all the necessary information so it looks as complete as the example below. 👇

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. 😍

Now, that you know when my birthday is, I really hope to receive millions (at least) of gifts on the 9th of June. 😇

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 your email address and keep it warm?

What the hell is a warm email address?

I hear you!

Essentially, email addresses can be at different stages depending on how you've been using your account.

Remember when we discussed domain reputation?

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

A warmed up email address is simply an email address that has been sending and receiving messages as a real person would do when creating his email address.

What's the process to warm it up?

You actually have 2 options:

1- The manual way

You need to send manual emails to your friends and acquaintances.

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 emails at scale.

It should look like something like this:

  • 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 those numbers may vary depending on who you're emailing and what does your complaint rate look like.

The big drawback of this method is the fact that it's really time-consuming. You also have no insurance that the people you email will actually reply to your emails.

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

We call it...

2- The automatic way

This approach will allow you to relax while your email address is getting warmed up.

The good thing with lemlist community is that it's the biggest online community around email outreach.

Hence, people often face the same problems and are always happy to help each other out.

In that specific case, we decided to build lemwarm, a feature in lemlist that will allow you to send and receive emails from other lemlisters. Yeah, that's how we call all our awesome users at lemlist. 😎

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 will send an email to other lemlisters using your account with some unique generated content (each message and subject is unique and generated via our smart content algorithm).

Since other people who'll be sending emails also have their account connected to lemlist, we will create conversations by replying to those messages with some more unique content (exactly as if you were doing it manually).

How do you setup lemwarm? Simply go to your user settings and click on "Enable email warmup".

email warm up

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

By adding such filters, you're also notifying Google that those emails are important to you. Hence, they should never go to spam which makes it an even better sign to get the best domain reputation possible.

If you're already a lemlister, I would advise to always keep that box ticked so you're sure your email address stays warm. 🔥

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

You know that time in every blog post that tells you that you can start your 14-day free trial if you want to become a superstar. 😎

This is it.👇

Start your free trial

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. 🤩

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 prospects’ inboxes.

It is impacted by 100s of different parameters. But, there are 5 parameters that 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 it’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.

Essentially, 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! 😇

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 the deliverability of your emails.

maximize email deliverability


That’s the number of people who put your message in the spam folder (it happens to even the best of us sometimes).

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. 😎

Bounce Rate

If you're sending emails to addresses that don't exist, your emails will bounce. 😩

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

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 use 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 “spammer,” ESP (email service providers) will put it on a blacklist.

That’s pretty much as bad as it sounds. Obviously, you’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. 😇

Here’s a nice tool you can use: https://lookup.mxtoolbox.com/blacklists.aspx

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

1) You’ve got a perfect reputation. Well done, champ. Now you can turn it up a notch.

2) You’ve been blacklisted. Well, crap. Sorry, bud. Getting yourself back in the email providers’ or ISP’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.

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.

However, link tracking and open tracking 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.

lemlist custom tracking

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.

Cold emailing is hard and sometimes time-consuming. But I promise you that spending a few extra hours will pay off in long-term.

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

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

Do your research.

Then, based on that research, craft your pitch.

Make it about them and not about you.

That way, you'll get much more replies and way less complaints. It's that simple!

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

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. ❤️

Take care lemlister 😎