Do spam words cause emails to go to spam?

No. Modern spam filters analyse hundreds of signals including sender reputation, authentication, engagement, complaint rates and sending behaviour. Individual words have very little impact on their own.

Is Tuesday always the best day to send emails?

No. The best sending day depends entirely on your audience, industry, campaign type and customer behaviour. Testing your own audience is far more valuable than following generic benchmarks.

Are open rates the most important email metric?

Not anymore. Since Apple Mail Privacy Protection and similar privacy features inflate opens, marketers should focus more on clicks, conversions, revenue and engagement.

Do images hurt email deliverability?

Not by themselves. Well-optimised images are perfectly acceptable. Deliverability problems are far more likely to come from poor sender reputation or low engagement than from using images.

Should every email be short?

No. The ideal length depends on the reader's intent. Promotional emails are often short, while newsletters, SaaS updates and educational content frequently perform well with much longer copy.

The Biggest Email Marketing Myths That Won't Die

There are two kinds of email marketing advice.

The kind that helps you send better campaigns. And the kind that gets repeated so often it sounds true — even when the evidence says otherwise.

The second kind is dangerous. Not because it's malicious, but because it feels reasonable. "Avoid spam words." "Send on Tuesday." "Keep emails short." These sound like sensible guidelines. Some of them were true a decade ago. A few were never true at all.

The problem isn't that marketers are lazy. It's that bad advice compounds. Someone writes a blog post. Another copies it. A hundred more repeat it. Eventually the myth outruns the evidence and becomes "best practice."

Here are the biggest ones. And what actually drives results.

Myth 1: Spam Words Cause Spam

This is the granddaddy of email myths. You'll still find entire websites listing "forbidden" words: FREE, BUY NOW, LIMITED OFFER, WINNER, GUARANTEE, CASH. The claim is that using any of these will trigger spam filters and tank your deliverability.

It's nonsense.

Modern spam filters don't work by scanning individual words. Mailbox providers like Gmail, Outlook, and Yahoo analyse hundreds of signals simultaneously:

Sender reputation — how have recipients treated your emails historically?
Domain and IP reputation — is your sending infrastructure trusted?
Authentication — do your SPF, DKIM, and DMARC records check out?
Engagement patterns — are people opening, clicking, and replying?
Complaint rates — are recipients marking you as spam?
Bounce rates — are you sending to valid addresses?
Sending consistency — do you send regularly or spike unpredictably?

The content of the email is one signal among dozens. A trusted sender can write "FREE SHIPPING" and land in the primary tab. A poor sender can write "Hello" and land in spam.

Litmus testing confirms this. Inbox placement depends almost entirely on sender reputation and authentication, not individual words. The "spam word list" industry exists to sell you tools you don't need.

Stop worrying about individual words. Start worrying about whether people actually want your emails.

Myth 2: Tuesday at 10am Is the Universal Best Send Time

Every few months, another study claims to have cracked the code: Tuesday at 10:00 AM is the perfect send time. Some say Wednesday. A few say Thursday. The specific time varies, but the promise is the same — hit this exact window and your opens will soar.

If it were that simple, every brand on earth would send on Tuesday morning.

The reality is more complicated. ContactMonkey's 2026 Internal Email Benchmark Report analysed 255,000+ campaigns across 20 industries and found five distinct timing clusters. Friday dominates for automotive, banking, construction, healthcare, and manufacturing. Tuesday wins for airlines, education, insurance, legal, and technology. Monday leads for agriculture, retail, transportation, and utilities.

Different audiences, different schedules, different behaviour.

A B2B SaaS audience checks email during working hours. Parents read newsletters after bedtime. Retail shoppers browse on evenings. Weekend hobbyists engage on Saturdays.

The best send time for your audience is the one you discover through testing. Not the one someone else found for their audience.

Myth 3: Open Rate Is the Most Important Metric

Open rate used to be the gold standard. You'd send a campaign, check opens, and judge performance accordingly.

Then Apple Mail Privacy Protection arrived in 2021 and broke it.

Apple's feature automatically pre-fetches email content, including tracking pixels. That means many "opens" are recorded even if the subscriber never looked at the message. Some industries have seen open rates inflate by 20 to 30 percentage points after the change.

Open rate isn't useless. It still tells you something about subject line performance and list health. But it shouldn't drive major business decisions.

Better metrics to prioritise:

Metric	Why It Matters
Click-through rate	People actually engaging with your content
Conversion rate	Clicks turning into desired actions
Revenue per email	The only metric that pays the bills
Unsubscribe rate	Whether you're losing subscribers
Complaint rate	Early warning for deliverability problems
Replies	Genuine human engagement

If your open rate is 45% but your click rate is 0.3%, you have a subject line problem, not a content problem. The opens aren't translating to action.

Open rate tells you whether your subject line worked. Everything else tells you whether your email worked.

Myth 4: Images Hurt Deliverability

This myth has roots in the early days of email marketing, when brands would send image-only emails — one giant graphic with all the text baked in. Spam filters flagged those because there was no live text to evaluate.

Today, images aren't the problem. Poor emails are.

Brands send beautifully designed, image-rich emails every day without deliverability issues. The key is balance:

Use live HTML text alongside images, not instead of them
Add alt text so the email makes sense when images don't load
Optimise file sizes so the email renders quickly
Don't rely on a single image — break the design into multiple elements
Test dark mode — images that look great on white backgrounds can disappear on dark ones

The real deliverability killer isn't images. It's sending irrelevant content to people who didn't ask for it.

Myth 5: More Personalisation Always Increases Performance

Adding someone's first name to a subject line isn't magic. Most subscribers barely notice. Sometimes it even reduces trust — especially if the name is wrong, misformatted, or feels forced.

Compare these subject lines:

Alex, your order has shipped

versus

Your order has shipped

Both communicate the same thing. The name doesn't add value. It adds clutter.

Personalisation that actually works is behavioural, not cosmetic:

Segment by purchase history — send relevant product recommendations
Segment by engagement — reward active subscribers, re-engage dormant ones
Segment by lifecycle stage — new subscribers get different content than long-term customers
Trigger by behaviour — abandoned cart, browse abandonment, post-purchase follow-up

Good segmentation almost always beats superficial personalisation. A relevant email sent to the right segment outperforms a personalised email sent to everyone.

Myth 6: Bigger Lists Mean Better Results

Many companies obsess over subscriber count. "We added 5,000 new subscribers this month" sounds like progress.

It isn't — unless those subscribers are engaged.

Consider two businesses:

Company A:

500,000 subscribers
6% open rate
0.2% conversion rate

Company B:

35,000 subscribers
45% open rate
5% conversion rate

Company B is making more money with 14 times fewer subscribers. That's not an edge case. It's the norm.

A large, unengaged list actively hurts you. It lowers your sender reputation, increases bounce rates, and skews your metrics. You're paying your ESP for subscribers who never open, never click, and never buy.

Cleaning your list isn't losing subscribers. It's removing dead weight so the subscribers who matter actually see your emails.

Myth 7: You Should Never Email Too Often

"How many emails is too many?" is the wrong question.

The right question is: "Is each email providing value?"

Some brands send daily and maintain strong engagement. Others send monthly and still see healthy open and click rates. Frequency isn't the variable. Relevance is.

Subscribers don't unsubscribe because you emailed them. They unsubscribe because you emailed them something they didn't care about.

The Litmus 2025 State of Email report found that frequency complaints are almost always tied to content quality, not send volume. Brands that send useful, targeted content can email daily without backlash. Brands that send generic blasts once a month still get unsubscribes.

Frequency becomes a problem when value decreases. Not when it increases.

Myth 8: Unsubscribes Mean Your Campaign Failed

Unsubscribes feel like failure. Nobody wants to lose subscribers.

But unsubscribes are healthy. They're your list self-regulating.

People change jobs. Interests evolve. Needs shift. A subscriber who was perfect two years ago might be completely irrelevant today. Keeping them doesn't help — it hurts.

Disengaged subscribers:

Lower your open rates — dragging down your reported performance
Reduce deliverability — mailbox providers see low engagement as a signal
Skew your metrics — making campaigns look worse than they are
Cost you money — you're paying your ESP for people who never engage

Sometimes the best subscriber is the one who leaves cleanly instead of marking your email as spam. An unsubscribe is a polite exit. A spam complaint is a disaster.

A healthy list isn't a list that never shrinks. It's a list where the right people stay.

Myth 9: More CTAs Mean More Clicks

Some marketers believe six buttons give six opportunities to convert.

They're wrong. Six buttons create six decisions. And confused readers often choose none.

The highest-performing emails typically have one obvious action. One button. One clear next step.

This isn't about limiting yourself. It's about reducing friction. When you give readers a single, focused path forward, they're more likely to take it.

Test it yourself. Send the same email with one CTA versus three. Track clicks on each. You'll almost always find the single-CTA version outperforms.

Clear beats clutter. Every time.

Myth 10: Every Email Must Be Short

"Keep emails under 200 words" is one of the most repeated pieces of email advice. It's also one of the least useful.

An abandoned cart email? Short works. One or two sentences, a product image, a button. Done.

A product announcement for a SaaS feature with screenshots, benefits, and use cases? That's 300 to 500 words. And it should be.

A detailed newsletter with industry analysis, trends, and actionable advice? That can be 1,000 words or more. Readers subscribed because they want the depth.

Constant Contact's study of 2.1 million customers found marketing emails peak at roughly 200 words for click-through rate. But that's an average across all email types. The optimal length depends entirely on the objective.

The right word count is the one that helps someone make a decision. No more. No less.

Myth 11: You Need a Perfect 60/40 Text-to-Image Ratio

This myth refuses to die. You'll still find marketers obsessing over whether their email is 60% text and 40% images.

Modern spam filters don't calculate image ratios. They ask bigger questions: Does this sender normally get engagement? Are recipients complaining? Is the sender authenticated? Is the domain trusted?

Good HTML structure matters. Using alt text matters. Ensuring your email renders when images are disabled matters. But counting pixels to hit a specific percentage doesn't.

Email on Acid's deliverability research found no correlation between image-to-text ratio and inbox placement. The relationship between images and deliverability was largely debunked years ago.

Focus on making emails that work. The ratio will take care of itself.

Myth 12: Sending More Emails Hurts Deliverability

Sending bad emails hurts deliverability. Sending good emails consistently improves it.

Mailbox providers want engaged users. If recipients regularly open, click, reply, and move your messages out of spam, your reputation improves. If they ignore, delete, or complain, it drops.

Volume isn't the variable. Quality is.

Gmail's Postmaster Tools documentation confirms this: sender reputation is based on engagement patterns, not send frequency. A brand sending 50 well-targeted emails per day will outperform one sending 500 untargeted blasts per week.

Consistency matters. But consistency of value, not consistency of volume.

Why These Myths Survive

Email marketing changes slowly. Advice doesn't.

Someone publishes a blog post. It gets copied. Then copied again. Eventually hundreds of sites repeat the same claim, and nobody remembers where it came from. Many "best practices" are inherited assumptions that nobody bothered to verify.

The myths survive because they feel actionable. "Avoid the word FREE" is easier to implement than "build sender reputation through consistent engagement." Simple rules beat complex realities — even when the simple rules are wrong.

What Actually Works

Strip away the myths and email marketing comes down to fundamentals:

Myth	Reality
Spam words matter	Sender reputation matters far more
Tuesday is best	Your audience decides the best time
Opens equal success	Revenue and conversions matter more
Images hurt deliverability	Poor emails hurt deliverability
Bigger lists are better	Engaged subscribers are better
More CTAs increase clicks	Clear focus increases clicks
Short emails always win	Relevant emails win
More emails reduce inboxing	Valuable emails improve engagement

Before Your Next Campaign

Forget the mythical best practices. Instead, ask:

Is this email genuinely useful to the recipient?
Does the subject line accurately describe the content?
Would I open this if it landed in my inbox?
Would I click this?
Does it have one clear objective?
Is it easy to scan on mobile?
Am I sending this because it's valuable, or because the calendar says it's time?

If you can answer yes to those questions, you're already ahead of most marketers chasing mythical rules.

The Bottom Line

Email marketing isn't complicated because of hidden algorithms.

It's complicated because humans are.

People don't click because you avoided the word "free." They don't convert because you sent at exactly 10:03 on a Tuesday. They don't stay subscribed because you hit a 60/40 image ratio.

They engage because the message is relevant, trustworthy, and arrives at a moment when they can act on it. That's what mailbox providers increasingly reward.

Ignore the myths. Focus on building emails that people genuinely want to receive.

The algorithms tend to follow.