The Ultimate Cold Mailing Checklist

Let us start on where this knowledge comes from.

I used to work as a growth hacker for Nimley, a company that took care of lead generation for its clients using its expertise in email copywriting.

I was in charge in B2B acquisition there, and of course, my primary acquisition channel was also cold emailing. It was an amazing position as any innovation found on my end could be implemented on our clients’ side to improve the product.

The biggest problem we kept running into was the spam filters as we kept getting awful open rates (sub 20%) after a few hundreds of email sent.

Here’s precisely why it was such a problem:

  • You ruin a domain’s reputation, so the setup has to be redone on another domain name (it’s faster than cleaning it up)
  • You cannot make any precise prediction on the leads you can generate in a given time
  • In our case it was a huge account management time sink

That problem could break out on me and any client at any time so we had to find quick and actionable solutions.

Everything we found is condensed in this article and by applying them all, we went from a shaky and unsure 20% open rate to a steady 60%+ across the board.

We reached the 70K€ MRR using cold mailing as our main acquisition channel (90% of our leads).

Before you ask, yes the result does scale with volume, and I also explain why in this article.

Also, for my European compatriots, make sure to shoot only business emails to respect GDPR guidelines.

In all of our tests, we realized there is not a single trick that made us reach the inboxes but rather a combination of practices which I’ll call pillars here.

Moreover, if any of these pillars are shaky, you can be assured that your deliverability will be shaky as well.

Here are the pillars and the question they bring forth:

  • What it is the form (HTML, links, pictures…) ?
  • What is the actual message you’re conveying ? (prop value, fit with audience, etc)
  • Do you know if the emails you have actually exist ?
  • Are they business, personal or contact emails ?
  • How are you actually sending the emails ?
  • Are you sending 1000 mails per day at once ?
  • What platform are you using ? Your mailbox ? A newsletter manager ?
  • How do you know if your domain has a good reputation ?
  • Did you setup SPF and DKIM before sending your email ?

I will in the following address each pillar, giving you the keys to start a successful cold emailing campaign.

I say content broadly, there are two parts we should address : the form and the substance.

This part could be summed up by saying : create content which would make your audience engage with it, opening it, reading it and replying to it.

The issue, is that if your content doesn’t follow some specific guidelines, it can end up in spam even if you have the best copy.


HTML is perfectly fine but I strongly recommend not to have any links or pictures.

Some spam filters (gmail’s especially) are very strict about external resources linked add to an email, especially if that email is sent from an unknown source.

You can still have a signature but go for plain text ! The example below is what we used in our UK campaigns:

John Doe
Account Executive @Nimley
+44 (0) 444 4444333
29 Oxford Street, London


I cannot help you talking better to your audience, since you’re definitely in the better shoes to so. You have to make them feel like you’re actually talking to them one on one and that takes customer experience.

However, I can tell you that to get your copy to get into inboxes, you should NOT sell your product.

There are two reasons for that:

  • Spam filters are intelligent nowadays and can easily pick up on email copies that are too sales-oriented because of wording and structure. If you use words that are too salesy, combined with the fact that it is the first time that you contacted that mailbox, you’ll be heading right into the spam folder.
  • Automated sales pitches are running rampant everywhere. If you manage to be read, but your reader recognizes at first glance, the reader will likely put you himself in his spam folder. That means your domain reputation will take a huge hit.

Huge no-nos : “Save $X by subscribing”, “Offer of a lifetime”, “You’ll never want to miss this”

What should you do then ?

You should try and provoke a conversation however you feel right. We used a simple strong call to action to close the email out something like : “Do you have 15 spare minutes to talk about it this week ?”

Customization with your prospect information is crucial to do so, even if you only have their first name to work with.

Here’s a nugget from this April 2019 Backlinko study about outreach emails:

Result of a 2019 Backlinko study

The email structure we used for our prospection was pretty simple but effective. For reference, our target was targeted B2B CEOs:

  • Introduction — Few words
  • Company introduction — 1 sentence max
  • Problem presentation — 1 sentence
  • Proposition value — 1 sentence
  • Strong CTA — Few words

This is a prospecting email copy used back when we target the UK market. These were CEOs to whom we sent emails but never answered (not a good practice for domain reputation) but the structure is there.

Hi Anas,

We got in touch a few months ago hoping to learn more about your prospection strategy. I can’t recall getting a response, so I am trying again now to see if it is a more relevant time to speak.

At Nimley, we generate business meetings for you with targeted potential customers through leveraging data, and have helped 156 customers generate over 45M in transactions.

I speak with a lot of CEOs and sales managers in your market and am keen to understand more about how you prospect. I am sure there is a lot we could learn from one another.

Do you have time for a 5 minute call at some point over the next few days to discuss this further?



John Doe
Account Executive @Nimley
+44 (0) 444 4444333
29 Oxford Street, London

Email Validation

This one is pretty short and simple.

Make sure your email don’t bounce. Bounces are one of the primary stats picked up for domain and sender reputation. To do so there are many services, we mainly used Verifalia and only used valid emails.

You might cut your databases in half, but you’re actually just finding out its real size. The contacts left are the only one you can contact properly. Make sure to store bounced data to not shoot these emails ever again.

I cannot stress this enough, this is a huge cornerstone of cold emailing, DO NOT SEND ANYTHING TO UNVALIDATED EMAILS.

There are two ways you should go:

  • A very well known email management tool : Mailchimp, Mailjet, etc. They basically are favored in regards with spam filters.
  • Any other tool off the market (API, SaaS) or your homemade SMTP sending machine as long as you implement DELAYS and RATE LIMITS. The rule of thumb when you’re cruising is to send about 500 maximum per day per domain at a rate of 1 to 2 emails per minute.

Warming up your domain/IP for sending

Whether you’re using a dedicated IP or not, you have to build up your sending reputation by starting slow and gradually increasing your sending volume.

We did a linear sending protocol over two weeks to reach 500 emails per day, starting at 50 emails per day, adding about 30 emails in volume per day.

We also used a stricter protocol, described here by, a little bit more tedious to use, but works wonders.

If you need more volume, you should scale of off your domain name/IPs, while staying within the rate limits. Use other extensions of your website or names that are close.


Before anything, make sure you setup SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) for your domain name.

These are security and identity measures which gives you a bit of breathing room when building up your sender reputation.

Usually, you’ll be prompted by your sending service to do so as an option. For instance, if you’re using Gsuite, there are clear tutorials here for SPF and here for DKIM.

The setup is simply to add new DNS records with the values given by your mail provider service, and it takes no more than 5 minutes.

Gmass inbox tool

Domain reputation checking

When you have a dip in open rates, how do you know if it’s because of your content, or because of your domain getting flagged as a spamming platform ?

To answer that we used two tools that did the same thing on a different scale:

Gmass inbox

It’s a simple tool but super useful.
You send your emails to the list shown on the page, look for your email, and see if your email landed in spam or inbox.
Send a simple conversational email like “Hey how are you, how about dinner tomorrow ?” to the test boxes and see where you land.

  • If you landed mostly in inbox : your domain is fine !
  • If you landed mostly in spam : your domain has been flagged.

A quick overview of how intuitive Gmass’s tool is


GlockApps’ API helps you do the same thing but at scale.
I strongly recommend it (they don’t sponsor me but I wish) when you manage more than a few domains.
They also have automatic features in their UI to help you monitor your reputation if you don’t know how to use the API.

It can be tedious to set up correctly for a cold emailing campaign, but it can yield amazing results:

We managed to generate over 70K in MRR using only cold emailing as an acquisition channel at Nimley.

And that was with us iterating on these deliverability issues.

The result of these iterations is the following:

There are 4 pillars to cold emailing and your deliverability is linked on how solid they ALL are. For your pillars to be solid here’s your cheat sheet:


  • Do not sell your product, create a conversation
  • Customize your content
  • End with a strong CTA (Let’s have a chat, When are you available for a call ?)
  • Use a simple conversational subject (meeting request, call request, your problem with issue X)
  • No links, no pictures

Email Validation

Delivery Method

  • Maximum 500 emails/day/domain, 1–2 emails/minute
  • Start slow and ramp up over two weeks

Domain Reputation

  • Setup SPF and DKIM on your sending domain
  • Don’t mess the other guidelines up
  • Check your reputation regularly with tools like Gmass or GlockApps

There you have it ! You should now have a strong knowledge base to start your cold emailing campaign. The natural question is what comes next ?

You should have replies to deal with and different meetings scheduled.

We had very cool processes where the mails were routed directly to our CRM, with our prospects data being enriched automatically.

Maybe we’ll talk about it next time !

If you have any questions or suggestions, you can contact me directly at or on my social media.


Originally published at

Growth engineer @Quable —