Are your emails not getting the desired number of opens? Want to make your emails hard to ignore and get more opens, responses, and demos booked? If yes, this blog post is for you.

Let me assure you—email is NOT dead!
In fact, here’s Statistica’s estimate of email marketing revenue worldwide 👇

The truth is—that there are only two types of emails: A great email and an instantly-delete-spam email. You are better off avoiding the second category.

The best sales reps I’ve seen over the last 15 years have mastered the art of using emails to build a healthy revenue pipeline.

They have a fail-proof process: warm up the domain, write attention-grabbing subject lines, a hook-you-in opening sentence, a short but appealing message, and a compelling Call-to-Action (CTA). 

In this blog, we will focus on two key factors that impact your email open rates—email deliverability and subject lines.

Warm up your domain to improve email deliverability

If you've just registered your domain or if your domain has been inactive for a while, you need to warm up your domain as well as the mailbox before it's ready for outbound.

What is domain warming?

Domain warming is the process of training your domain and building a reputation to be a trusted sender. Just like you need to build sufficient positive credit history to get a home loan from a bank, new domains need to earn a good reputation with email providers, so that they can email large volumes overtime. 

Internet service providers (ISPs) like Gmail determine whether they should deliver your emails to the inbox or the spam folder of your recipient based on your domain reputation. It includes checking for blacklisted domains, consistency and volume of emails sent, positive email engagement, and more.

One such critical factor for domain reputation is age. 

It typically takes 8-12 weeks to accomplish maximum deliverability. If you start sending 100s of emails in the early days of your domain, the spam filters check the domain’s age, and when it’s younger than a month, they will mark it as suspicious by default.

Interestingly, starting February 2024—Google & Yahoo are increasing their protection standards with authentication, unsubscription and more for bulk email senders to make the inbox less spammy for recipients. Anyone sending 5,000 or more emails daily from their domain falls under the category of bulk senders.

So, domain warming becomes extremely important to build your domain reputation, especially if you’re using email as a key lead generation channel.

How does domain warming work?

When done manually, domain warming refers to a set of essential steps:

• Authenticate your account (SPF, DKIM, DMARC authentication) against spam filters
• Create a robust network of email senders and receivers
• Organically expand your contact list
• Maintain conversation threads
• Maintain a time gap between two emails
• Set up test campaigns

However, to save yourself from domain warming becoming a tedious and time-consuming chore, you can use email warmup automation tools that make things much easier. You can simply sign up for one of the warmup tools and become part of a network of real inboxes that communicate with each other.

Once you sync your inbox with any of the warmup tools, you can start sending emails to those in the highly engaged network. The people in the network open your emails, reply to them, mark them as important, and unmark them from spam (if applicable), building up your email ‘credit score’ and developing trust with service providers.

These tools typically help you track:

• Domain reputation
• IP reputation
• Spam rate
• Delivery errors

They help you keep tabs on the various aspects of your email health, from the percentage of emails ending up in spam through technical elements (the DNS settings, DMARC, DKIM, SPF, domain age, proper security protocols, etc.) to make sure you’re are not on any blacklists.

The above process creates a positive feedback loop, builds your domain reputation, and trains ISPs & Mail Servers to view your emails as valid and safe.

Even if you are using a warmup automation tool, we recommend the following best practices:

1. Don’t set up more than one email account in the first month. 
2. By the second week, send out simple conversational emails (not more than 2-3 per day) to the business emails of your contacts who will reply. The reply rates matter a lot, especially if your email provider is Gmail.
3. It’s best to set up your recipient emails with different email providers, such as AOL, Yahoo, Yandex, Gmail, Outlook, etc.
4. Once you do this for 2 weeks, you are ready to run a test campaign. You can build a list of 20 emails that you trust won’t bounce (ideally those who will respond to you) and run a test campaign using Plena.
5. Increase the number of emails gradually. Remember that even if your domain is old enough with an excellent reputation, sending campaigns in huge numbers may impact your domain’s credibility.

Now that we’ve seen how to ensure the delivery of your emails in the inbox, let’s get to the most dominant item that determines email open rates.

Subject line mistakes to avoid

What good are emails that land in inboxes, if no one opens them? Your perfect email body will never be read unless your subject line lures the recipient to open it.

State of the industry reports somehow have convinced us over the years that 20% open rates and less than 1% click through rates are normal. But that’s not true!

Majority of our customers shoot for 50% or higher, when it comes to open rates

What gets a person  to open any email—the subject line.

At Plena, we recently analyzed the subject lines of over 100K emails sent by our customer's bots last quarter.

Two of the most significant insights were:

49% of email recipients decide to open emails based on the subject line.
And 71.4% of emails were reported spam solely based on the subject line.

Let that sink in. Almost 72% reported spam, let alone opening the email!

So, we interviewed some of our customers (who were once prospects) to understand what makes them open emails. What factors do they consider?

It always came down to whether the subject line passed their mental spam filter to understand what the email was about and if it was a sales pitch.

They consider 3 things primarily:

• Sender’s name
• Subject line
• Preview text

Because we are talking about cold emails, the "sender's name" isn't a controllable factor unless you've built a relationship with your target list by engaging with them on LinkedIn or other forums.

While that's a topic for another day, let's get back to the subject line.

Multiple conversations pointed to shorter subject lines (not more than 2 to 4 words) worked the best, as they also made it easy for the recipients to view the preview text.

While shorter subjects work best, they shouldn’t be obviously salesy.
We’ve collated a few subject lines based on our experience that you might want to avoid.

Avoid these subject lines at all costs 👇

❌ Quick question

❌ <First name>, want xyz?

❌ Thoughts? (And any of the cliches)

❌ RE: (screams “shady”)

❌ 2x/10x revenue/conversion or anything merely transactional

Why do the above subject lines not work?

• Quick question/ Thoughts?/ RE: — These are done and dusted subject lines that make people automatically tune out or hit delete unless the email is from a known contact.

• Using a first name in the subject line is NOT personalization. It is actually a clear giveaway of it being an automated email. You wouldn’t usually use a first name in the subject when writing to someone.

• ROI and transactional subject lines — Surprising, right? You would think personalized, ROI-oriented subjects would actually help. But no! Such headlines, by default, go into the Promotion and SPAM category. For a minute, look at the subject lines below. Would you click and open any of those emails?

Crafting cold email subject lines that work

Subject lines are the first thing a recipient sees when they receive your email. It needs to grab their attention and encourage them to open the email. A catchy email subject line can entice the recipient to read further, click on links, or take other desired actions.

The best subject lines do three simple things:

• Tell you what the email is about
• Keeps it short
• Doesn’t make the recipient guess

Here are a few points to remember when crafting subject lines if the primary goal is to get recipients to open it.

• Clarity and relevance: Ensure subject lines are not more than 2 - 4 words. Make it clear and relevant, and ensure it directly conveys the email's purpose — similar to emails that are internal to your organization.
• Avoid clickbait: Take additional care that your subject lines are not misleading and don't contain language that may raise false expectations.
• Avoid caps lock: Avoid excessive use of capital letters as they may come across as impolite.
• Avoid jargon and superlatives: Steer away from using jargon and superlatives such as 'synergy,' 'improved,' 'accelerated,' etc.
• Avoid numbers, percentages, and symbols: From our experience, we would recommend that using questions, numbers, and percentages are to be avoided as well.
• Setting expectations: Set clear expectations in the subject line to reduce uncertainty for the recipient.
• Avoid sensationalism: Stay away from using sensational or alarming language that can cause unnecessary anxiety.
• Optimize for Mobile: This one is often missed. Keep in mind that many recipients view emails on mobile devices, so subject lines should be mobile-friendly.

Lastly, A/B test different subject line variations to understand what resonates best with your audience.

One of our customers  said it best:
‍
“Clarity over cleverness, any day! The purpose is to get open and not to win a stand-up title. The best subject lines are the ones that work on us. It’s much more effective to use subject lines similar to the ones we get from our teammates/ boss/ peers.”

According to Rain Group, 62% of prospects are open to emails when they're actively looking for a solution to their current challenges. So, when you're prospecting, your subject line needs to relate to their problem statements. It should make them open the email to see how you can help solve it.

Cold email subject lines that got us more than 50% opens

✅ Reply rate issues
✅ LinkedIn prospecting
✅ Low replies
✅ Next steps
✅ Intent based list in 3 clicks
✅ Best performing outreach templates
✅ This might help
✅ Does your outreach work?
✅ Find your potential buyers

The subject lines are based mainly on whom it is sent to. For instance, when you’re reaching out to founders who get tons of emails every day, you might want to grab their attention based on things that might be on their minds.

Here are a couple of founder specific subject line templates you might want to try:

✅ How <your competitor> does <your pain>? (based on FOMO)
Example: How ClickUp drives user adoption?

✅ Here’s how you <solve pain point> (generates curiosity)
Example: Here’s how you 10x your response rate

Remember to “say more with less”

Email subject lines, especially for sales, offer a lot of room to be creative. You can say a lot with fewer words, and it’s a fantastic opportunity to stay top of mind. But the first goal is always to get the email opened.

And once they’ve opened the email, and you have their attention, you want to keep your message crisp—they should be able to read it on their mobile without needing to scroll. 

In fact, Litmus research shows that recipients spend no more than 10 seconds on their emails. And the time seems to reduce every year.

Checkout our other blogs to find thoroughly researched content on sales email frameworks and potential pitfalls in lead generation via email.

Lastly, please let us know if you found this post helpful.