20 Common Email Marketing Mistakes to Avoid

Lyn McNamee -

Why isn’t my email marketing getting results?

It’s a common question bugging marketers all over the world. You’re sending marketing emails to your list but you’re getting tiny click-through rates. Why?

Are your emails ending up in a spam folder because you’re making elementary errors? Or are people ignoring your emails because they don’t like the content? Is your subject line the problem? Or is it that your emails don’t look great on mobile devices?

The answer is likely linked to one or more of these 20 common email marketing mistakes. This list will help you pinpoint whether you’re making one or more of these mistakes and how to fix the problem.

Let’s dive in and see what might be going wrong.

Table of Contents

Strategy & Planning Mistakes

#1. Not having a clear goal

Do you know what you want to achieve in your email marketing campaigns? Sending emails without knowing what you want your audience to do (e.g., click, buy, reply, etc.) automatically creates a problem because your messaging won't lead your potential customers down the right path.

Think about this scenario: a part-time jeweler running a small eCommerce store selling her own creations. Let's call her Sarah.

Sarah sends customers on her list a monthly newsletter. However, she can't decide whether she wants to encourage people to buy, follow her on Instagram, or read her blog. As a result, her emails feel scattered and confused and very few people feel motivated to follow up.

How to fix this problem - understand your email marketing strategy
  • Decide what you want to achieve before you write your email
  • Create content that relates to your goal and gives readers a reason to follow up
  • Include a compelling CTA (see Technical Mistakes)

#2. Ignoring segmentation

Are you treating your entire list the same? They’re not all in the same frame of mind or in the same place in your funnel. So sending the same email to everyone means it’s likely to be too much info for some but too little for others.

An introduction might be just what your beginners need but irrelevant for advanced users. That in-depth dive into customer relationships might be spot on for those who’ve taken your course, but is lost on people who are still deciding whether to buy.

Ignoring segmentation leads to poor relevance and lower engagement.

Consider a B2B SaaS startup sending a technical product update to their entire list—including non-users and first-time leads...I bet you can see where this is going.

Their target audience of longtime users is pleased to hear about the update and many click the link. The rest don’t care, feel confused, get annoyed... any or all of which causes a spike in unsubscribes.

How to fix this problem - sort your subscribers
  • Segment your email subscribers into relevant lists such as experience levels, customer journey stage or frequency of use.
  • Create relevant content for each list. For example, you might send how-to and FAQ content, ads and discounts to beginners, but industry insights and early access to beta testing groups to your advanced segment.

#3. Sending without consent

Adding people to your list without permission is an absolute no-no!

Apart from the fact that doing so can tank your deliverability it will also violate regulations in the EU, US, UK, Australia, Canada and many other countries, including several in Asia and Africa.

For example, what if our jeweler, Sarah, imports contacts from her LinkedIn connections into Mailchimp and starts sending everyone promotional emails? It might seem like a great way to bump up her list but at least half will immediately mark her emails as spam because they know they didn't sign up for that.

Even worse, some might lay privacy complaints. If they’re upheld, Sarah could be in for massive fines. For example, in the US the Federal Trade Commission can impose civil penalties of up to $51,000+ per email that violates the law. Ouch!

How to fix this problem - use a double opt-in process

There’s a strong global trend towards information privacy and consent. Best practice: get consent via a double opt-in process.

  • Send a confirmation request after someone signs up for your email list. Do this no matter whether they're signing up to get your newsletter, a lead magnet or anything else.
  • Confirmation proves consent (if there's a query), reduces fake sign-ups from bots and keeps your list clean and lean (so you're only paying your email service for people who want to hear from you.)

Cleaner lists mean fewer bounces and a better sender reputation. Email providers like Gmail and Outlook watch out for this, and so should you.

#4. Not defining your audience persona

You need clarity on who you’re emailing and why, because vague targeting equals vague results.

Here’s what I mean: imagine a coaching business blasting out vague motivation quotes to a list that includes CEOs, students and HR managers. Not one of these groups feels like the message is for them. Result? No-one gives them more than a passing glance. Over time, they completely disengage and eventually the business is flooded with unsubscribe requests.

Sending generic emails to everyone probably means your emails won't resonate with anyone on your list.

How to fix this problem - know your audience!

Build a clear picture of the person you want to reach — not just their job title, but what they care about, what problems they’re trying to solve, and how your emails can help.

  • Create a mini character profile for your ideal subscriber. Think about your products or services—what problem(s) do they solve? Who has those problems? Who did you design them for? That’s your ideal customer.
  • Send content and marketing emails that speak directly to that person. If you get feedback saying ‘it’s like you’re reading my mind’, you’re on the right track.

Learn about your customers by talking to them.

Contact people by:

  • Asking a question in your newsletter and inviting them to reply
  • Conducting a survey
  • Posting a quiz
  • Commenting when they visit your social media platforms
  • DM-ing those who seem particularly engaged and asking for a quick chat

Once you know your audience persona, go back to #1. What’s your newsletter’s goal? Are your goal and content relevant to this audience?

#5. Inconsistent sending schedule

Sending too often, too rarely or inconsistently can either annoy subscribers or make them forget you all together.

Say a local gym sent three emails in one week, then nothing for two months? After two months most people don't remember signing up and hit unsubscribe or send it to the spam folder. Either way, that gym's message isn't getting through.

How to fix this problem - send regular emails
  • Decide on a regular cadence. That might be daily, weekly or even monthly—so long as it's a schedule that suits you and your audience.
  • Include the schedule on your sign up forms (e.g. 'twice weekly emails' or 'we'll drop you a line each week' or 'once a month you'll get a sneak peek into our upcoming specials.' and in your welcome email.

Content Mistakes

#6. Weak subject lines

If your subject line doesn’t grab attention, the rest doesn’t matter. You might have written a masterpiece but it’ll remain unread if people don’t open the email.

Let’s pretend our local gym has fixed their scheduling problem and now sends a monthly email with inspiring stories, special offers and helpful hints on topics their customers love. It should be a winner except for one problem.

They choose a simple subject line: “March Newsletter Inside!”

Practical? Yes.

Enticing? Engaging? Thought provoking? Hinting at the content?

No! The open rate is under 10% and they’re left wondering what went wrong.

How to fix this problem - give people a reason to click
  • Think of your subject line like a movie trailer sparking curiosity or hinting at what’s inside.
  • Don't descend to clickbait titles. Speak to your audience and offer something valuable or intriguing.

Instead of that ho-hum subject line, our gym's marketing team could try these subject lines, each of which gives the reader a peek at what’s coming and a reason to care.

  • “Meet Jane, who ran her first 5K at 63 (How she did it!)”
  • “3 ways to boost energy without changing your workout”
  • “Your March motivation is here 💪”
  • Test different subject line styles and ask yourself: Would I open this?

#7. Overloading with information

Watch how much information you're sending at a time. Too much text can be overwhelming and many readers will bail out as soon as they see it.

Likewise, having too many calls to action can be confusing if they lead to different outcomes, or annoying if you face a ‘buy now’ button after every paragraph. (I don’t know about you, but I tend to feel yelled at.)

Let's imagine this in action:

A nonprofit has oodles to share with its audience. They've had excellent results with some programs, but see a pressing need in others. So, they cram it all into this month's newsletter.

Suddenly, they have four articles, three donation requests, two event invites, and a paragraph from the director—all in one email.

It just won't work.

How to fix this problem - create a content marketing calendar

A simple content calendar helps you plan what to say and when. Each email has one clear focus and your readers don’t feel overwhelmed.

Our nonprofit could adjust their schedule and send short weekly notes.

  • Week 1: Share the success story and include a donate button
  • Week 2: Highlight the upcoming event with an RSVP link
  • Week 3: Send a behind-the-scenes note from the director, with another donate button
  • Week 4: Offer a volunteer spotlight or helpful resource and a CTA to follow the nonprofit on social media

Each email has one job to do—and does it well. There's no need to scramble for content every month, either. Each time stories or events information comes in, file it in the best category, and publish as needed.

#8. Lack of personalization

A first name merge tag used to be enough.

Not any more. Now, you need to tailor content based on behavior, preferences, or past actions.

Let’s say an online bookstore sends out a promo email with an enticing subject line: “Books You’ll Love.” Inside, the email lists six new releases… all crime thrillers.

But Jane, who’s on their list, only ever buys cookbooks. She rolls her eyes, clicks unsubscribe and heads to another online bookstore. After all, there are plenty of them about.

That’s the problem with weak personalization. It really misses the mark and risks driving customers away.

How to fix this problem - learn to use your email provider's segmentation tools

I was out of my depth when I first started considering personalized content. It seemed like an awful lot of work—and it would be if I had to do it all myself. Fortunately, ESPs have automated the process.

For example, most ESPs allow click tracking, which means you could segment your audience based on what they click. In that setup, we'd tag Jane with "food" or "cookbooks." Then future campaigns would send Jane recipes and cook book recommendations, and only thriller fans would get the next page-turner.

#9. Being too salesy

If your marketing materials are constantly pitching for sales instead of offering value, people on your list will quickly end up with one of two reactions. They'll either tune out or unsubscribe.

So, imagine you're marketing a skincare brand. You're desperate for sales so every email screams “Buy now!” To make matters worse, you don't offer any educational content.

What happens? People who like your product sign up but after your welcome email their engagement plummets. Staying on your list but ignoring your emails costs you money (because ESPs charge by list numbers) and reputation. Remember, Google and Outlook notice these things.

How to fix this problem - include engaging content

Content marketing is all about engaging and educating the reader and giving them a reason to buy. It's a long-term game, where people come to trust you and your brand over time, as they receive more and more helpful content.

  • Our skincare brand could offer exclusive content, helpful beauty tips and make-up profiles for different skin types or coloring.
  • Sarah might send tips on cleaning jewelry, fascinating insights into her design process or clever ways to accessorize using some of her iconic pieces.
  • That online bookstore could include book reviews, round-ups, author spotlights and interviews, book bundles and recommendations.

#10. Ignoring mobile optimization

Digital marketing might work well on computers, but don't forget to format for mobile users too. Many people check emails on their phones. Others prefer tablets. So, if you ignore these other devices, your marketing plan is in trouble. Bad formatting equals lost opportunity.

For example, each month an investment firm sends a long newsletter heavy with performance tables, rate comparisons and account summaries. These wide tables and tiny font look great on desktop but disastrous on mobile. It doesn't take long before readers get frustrated and (you guessed it) unsubscribe.

How to fix this problem - use email templates with responsive design

UX (user experience) is all about easy, enjoyable, and effective interaction. That means optimizing for all devices by using responsive design. That means:

  • The email looks great on any device
  • Images load quickly and adjust to mobile devices, tablets and laptops
  • Font is easy to scan and read without zooming
  • All links and buttons work quickly and are easy to tap

Technical Mistakes

#11. No A/B testing

If you’re not testing subject lines, content, or send times, you’re missing chances to improve.

Without A/B testing, you’re basically guessing what works. Testing lets you compare two versions of your email to see which one gets more opens, clicks, or conversions—so you can stop guessing and start improving.

What if Sarah always sends her emails at 9 a.m. on Tuesdays and never tests her subject lines? But most people on her list are at work by 9am, and not thinking about jewelry. She'll never learn that a different time or a more relent subject line could double her open rate unless she tests.

How to fix this problem - test your decisions

ESPs like Mailerlite, Mailchimp and Kit include A/B testing (aka split-testing) as part of their packages.

Mailerlite defines split testing as:

"Sending 2 different versions of your email to a sample of your email list to see which version performs better. The version that receives the most engagement is then sent out to the rest of your list.

Some ESPs allow multivariate testing where you check several different versions of an email campaign at the same time.

So:

  • Try two subject lines to see which gets more opens
  • Test different layouts, copy, or images to see what drives more clicks
  • Experiment with send times to find when your audience is most active
  • Make decisions based on real data to get the best deliverability, opens and click-through rates possible.

#12. Not monitoring deliverability

Nasties like spam traps, blacklists, and low engagement can destroy your sender reputation.

Spam traps are fake email addresses used to catch senders using poor practices, e.g. buying address lists or emailing old contacts. Meanwhile, blacklists are databases of known spam senders. You don't want to end up on one because your emails may go straight to spam or, even worse, blocked altogether.

Remember how I said inbox providers (like Gmail) take notice of what happens to your email marketing or newsletters when they land in people's inboxes? Low engagement (people not opening or clicking) shows your messages aren’t valuable, which hurts your deliverability over time.

Picture Emil, a travel blogger whose weekly newsletter forms the backbone of their business. One week they check their analytics and find their open rates plummeting. A frantic investigation reveals their domain was flagged for spam thanks to poor hygiene and frequent mass sends. Ouch.

How to fix this problem - protect your sender reputation

Your sender reputation is like your email credit score and affects whether your messages reach the inbox or head to spam. A clean, engaged list keeps your emails out of trouble and in front of real people. So:

  • Don't buy or scrape email lists
  • Regularly remove inactive subscribers
  • Only send content people actually want to open and engage with
  • Use double opt-ins to avoid fake or mistyped addresses
  • If you haven't checked your list before, consider using an email list verification service like Zero Bounce or Mailbox Validator to scrub it clean.

#13. Missing or weak CTA

Your call to action guides readers toward doing something—whether it’s clicking, buying, signing up, or learning more.

If readers aren’t clear on that next step, they won’t take it. It's as simple as that.

For example, what if you regularly bury "check out our website" at the bottom of a long email? Few people scroll that far so they won't have any idea what to do next. What happens?

Most readers do nothing and you lose potential customers.

How to fix this problem - use strategic calls to action

Cap off a successful email campaign with the best-possible click rates by including strong CTAs placed where readers are sure to see them.

  • Use an action-oriented CTA. E.g., “Explore our latest collection” rather than “Click here to visit our website.”
  • Make it stand out with buttons or bold styling
  • Place it logically—after you've delivered value, but before readers drop out
  • Use one primary CTA per email to avoid decision fatigue

#14. Using too many images or huge files

Filling your emails with large files and too many images can trigger spam filters not to mention slowing down loading times. We’re an impatient lot, and most of us won’t wait more than a few seconds for an email (or website) to load.

Here's a scenario: an interior design company has taken to sending image-heavy newsletters way over Gmail's 102KB limit.

On their end, the kitchen, bathroom and living area photos look amazing and highlight their unique style.

On their readers’ end newsletters take forever to load, and recipients bounce before reading. Alternatively, Outlook users see a badly loaded, disjointed email and Gmail clips it (cuts off the bottom part of the email) and half the readers don’t bother opening the “View entire message” link.

Either way, they're losing sales by not living up to customer expectations for clean, quick-loading emails.

How to fix this problem - reduce image sizes and design for speed

Optimizing images and limiting large files helps your content load faster and stay visible in all inboxes. You can:

  • Compress images before uploading (try tools like TinyPNG or Squoosh)
  • Save images in web-friendly formats like JPEG or WebP for photos, and PNG for graphics with transparency
  • Balance images with text so your message is still readable if images don’t load
  • Check that you're under Gmail’s 102KB clipping limit before you press send.

#15. Broken links or buttons

How many times have you seen a "here's the correct link" email from your favorite creator or company? More than once, I bet. You might forgive occasional outdated, incorrect or broken links now and then, but not for long. And certainly not if you've just signed up to their list.

A broken CTA means you've wasted all the effort you put into writing the email.

Imagine Sofia a fitness influencer who's spent weeks putting together a free e-book as a lead magnet for her new course. But when she starts her email marketing campaign the “Download Now” button sends her fans to a 404 page.

If she's lucky, some kind readers will alert her to the error. Others will write complain. Still more will shrug and do nothing. Whatever happens, she's likely lost potential customers with that slip-up.

How to fix this problem - test before you send.

This one's simple.

Send yourself a test email before you send it to your list. That way you can check every link before you schedule send.

Analytics & Feedback Mistakes

#16. Not tracking performance metrics

If you're not reviewing open rates, click rates, and conversions, you're flying blind. Without tracking, you won’t know what’s working, what’s falling flat, or how to improve future campaigns.

For example, Liam sends weekly emails curating the news on cutting-edge technology. But because he never looks at open or click-through rates, Liam has no idea which topics people care about the most and which ones many of his readers ignore.

How to fix this problem - check email analytics

Don’t guess. Track the right data and use it to fine-tune your marketing emails.

  • Use your ESP's built-in analytics to track key metrics—open rates, click-through rates, conversions, and unsubscribe rates—to measure real engagement
  • Set clear goals for your marketing campaigns (e.g., more webinar signups, more purchases.) Refer back to those goals when analyzing your key metrics to help judge a successful email campaign.
  • Compare email performance over time to learn what topics, styles, and send times work best.

#17. Ignoring unsubscribe requests and spam complaints

These are signals something’s wrong, so what's the underlying issue? Why are people leaving? Why are your emails ending up in their spam folder?

Perhaps you're making several of the marketing mistakes on our list? Brushing off these warnings can hurt your sender reputation and make it harder for your emails to reach the inbox at all.

Let's say a fashion brand is sending fortnightly product emails to their list. Over the past three months they've seen 20 unsubscribes per email. But instead of investigating, their marketers shrug it off as normal.

How can they know for sure unless they investigate?

How to fix this problem - listen, learn, and adjust
  • Survey unsubscribes to find out why they left. Many email platforms let you add a simple "Why are you unsubscribing?" question to the unsubscribe process.
  • Examine your email content and format. Did you change something that might have prompted this rash of unsubscribe requests?
  • Are you segmenting your list properly? (#2)
  • Do your links work properly? (#15)
  • Check your list health (#12)
  • Analyze key metrics to see past and present click-through rates (#16)

#18. Failing to clean your list regularly

Old, inactive email addresses hurt deliverability and skew your metrics.

Internet service providers (like Gmail, Outlook, and Yahoo) will notice when a large portion of your emails aren’t being opened, clicked, or even delivered. That lowers your sender reputation, making it more likely that even your active subscribers will stop seeing your emails in their inbox and start finding them in spam instead.

It also messes with your metrics, making it harder to tell what’s actually working because your open and click rates will look way lower than they really are.

Picture this: more than half of Maria’s list hasn’t opened an email this year. Maria takes great pride in having such a big list, so she ignores the open rate and keeps sending emails to everyone. As a result, her deliverability score takes a hit, and her emails land in spam folders. Genuine readers don't see Maria's emails and over time they forget about her and her business.

How to fix this problem - give your list a six-monthly scrub
  • Look for people who haven’t opened or clicked an email in the last 3–6 months
  • Send them a re-engagement email reminding them why they signed up and asking if they still want to hear from you. Some people offer a special deal in these emails.
  • If they don’t respond to the re-engagement, delete them
  • Consider using an email verification service to find invalid or risky addresses that could harm your sender reputation (#12)

#19. Not welcoming new subscribers properly

A strong welcome sequence sets the tone for new subscribers. It sets them up to remember you, gives them an idea of what to expect from your emails and boosts long-term engagement.

Conversely, not sending a welcome email (or email series) can leave your readers feeling unwanted or disinterested.

Let’s imagine you subscribed to a boutique travel agency’s mailing list expecting to get tips for your upcoming vacation. They don’t have a welcome sequence in place, so even though you confirmed your address, you hear nothing for weeks.

By the time you finally get a promo, you’ve forgotten who they are and why you signed up. Anyway, your vacation's been and gone, and they've given you no reason to stick around, so you hit unsubscribe.

How to fix this problem - set up automated email sequences
  • Plan a brief series of emails to introduce your brand, highlight useful content, set delivery expectations and so on.
  • Automate the flow, so your first email arrives as soon as people confirm their subscription, with the others spaced a few days apart.
  • Make your emails feel like a natural conversation. Welcome emails often include questions like "What's your biggest challenge?" The reply gives you more information to help with segmentation and sending relevant emails after the sequence has finished.
  • Consider offering new subscriber discounts or bonuses to encourage more engagement and bring the subscriber further into your brand's world.

#20. Neglecting to test across email clients

What looks great in Gmail might break in Outlook so do some essential cross-client testing before you press send.

Let’s pretend that Sarah sorted all her other email issues and now has a beautifully designed monthly template. Her newsletter looks perfect in Gmail but breaks in Outlook and half Sarah’s list gets an unreadable mess.

With luck, a reader will let Sarah know what's happening. If not, her Outlook users will probably unsubscribe.

How to fix this problem - use a checklist before you send

Preview your email in desktop and mobile views and send test emails to different accounts (Gmail, Outlook, Yahoo, Apple Mail, etc.) to:

  • Check images and logos load properly
  • Test all links and buttons
  • Are font styles and sizes readable on all devices?
  • Look for layout or spacing issues (because some email clients may shift your design slightly)
  • Review dark mode appearance (some platforms invert colors)
  • Confirm your subject line and preview text are displaying correctly (no weird cut-offs).

If that sounds overwhelming, consider a tool like Litmus or Email on Acid (both offer a free trial) to check your emails across many devices and clients.

Final thoughts

Having a few aha moments as you read through our list?

That’s a good thing. It means you're already on your way to stronger email marketing. The best campaigns come from keeping your list clean, your content on point, and your reputation shining.

Want another smart way to grow? Try reaching new audiences by sponsoring newsletters they already trust. Use Reletter to find the perfect newsletters in your niche.