Nailing your subject line, preview text and email campaign means nothing if your recipients never see it. So, how do you make sure they do? While no one can guarantee your emails won’t be filtered to spam, we’ve compiled 6 best-practice tips to help avoid the spam filter, so your campaigns are more likely to be seen, opened and generate leads.

Just quickly—What is Spam?

Spam is an irrelevant or unsolicited email, sent to a large number of recipients, for the intended purpose of marketing and advertising (or something more sinister).

The main criteria spam filters consider when judging each email that comes through to the recipients inbox includes:

  • Campaign metadata
  • IP address
  • Coding within the email
  • Content & formatting

So, how do you avoid having your campaigns auto-filtered to spam? Here’s a quick run-down, then we’ll go into more detail for each point:

  1. Don’t purchase email lists, not even from ‘trusted’ sources
  2. Avoid ‘salesy’ trigger words (and these other language triggers)
  3. Keep your list clean
  4. Keep your emails short
  5. Proof before you send
  6. Find your frequency sweet spot

Okay, let’s find out how to avoid the spam filter when sending marketing emails to your database.

1. Don’t purchase email lists, not even from ‘trusted’ sources

It’s at the top of our list because it is the most important point: send your emails to those who want to hear from you. This is the building block to ensuring your marketing emails get read and you get leads!

A big no-no in the email marketing world is purchasing email databases. This is a sure-fire way to get marked as spam by your recipients. Simply put: bought lists mean those people don’t know you or your business, and so don’t want your emails.

Instead, market to your current customers or those who have expressed interest in your business. These people are much more likely to open and engage with your marketing emails, which is a win-win on both sides!

You also want to avoid sending marketing emails to:

  • Anyone who has previously unsubscribed from your list
  • Any emails you’ve scraped from other websites
  • Anyone who has previously hard bounced (meaning the address is invalid, closed or non-existent)

Don’t have a database? You’d be surprised.

2. Avoid ‘salesy’ trigger words (and these other language triggers)

Spam filters are getting smarter. Once upon a time, marketers would simply avoid a few key phrases here and there to ensure their emails landed in the inbox. Now, the best way to get to the inbox (and avoid the spam filter) is to be relevant and human.

So, what does that mean? It means a few things.

Avoid these spam-favourite phrases

While spam filters are advancing, they still flag your email as spam if you stuff it with certain spammy phrases. Think of it this way: if it’s something a telemarketer will say to you, it’s probably spammy.

According to, you should avoid words such as: advertisement, business, cash, cheap, commodity, congratulations, credit, deal, debt, degree, disclaimer, discount, free, gimmick, guarantee, income, ink, investment, joke, load, marketing, merchant, money, obligation, offer, opt, opportunity, outstanding, payoff, price, profit, promo, promotion, rate, refund, rich, sales, save, shop, spam, spree, stock, subscribe, trading, wealth, win, winner, winning, and won.

Find more trigger words here.

Avoid using all caps

Don’t yell at your audience, no one likes it and it comes across as aggressive.According to a study by the Radicati Group, 85% of people prefer their subject lines to be all lowercase, rather than all uppercase. So it’s important to refrain from hitting that caps lock button.

Using all caps may work to get their attention, but it looks aggressive and can be annoying. Instead, accentuate your news in other ways, like using exciting language, personalise your email and being relevant to the recipient.

Avoid exclamation points

Sure, you may find your message exciting, but using excessive exclamation points only works to dilute what you want to say. Having multiple exclamation points in a row in your subject line, preview text or even inside your email is an immediate red flag not only to the spam filter, but also your recipients.

So even if you get past the filter, you’re limiting your open rates by coming across as spam.

3. Keep your list clean

People change. They create new email addresses, become interested in different things, and sometimes… just stop engaging. That’s ok. That’s expected. Typically, each year your email database will degrade by about 22%. So, it’s important to keep your list as clean as possible and focus on the people who will actually open your emails.

Sending emails to outdated or closed addresses can negatively impact your deliverability, which means your emails are more likely to go to spam or, if it’s bad enough, your IP could be blocked completely.

Find out why you should clean your email list and how to do it here.

4. Keep your emails short

When crafting your email content, make sure you don’t go overboard. 150 words is compelling and easier to get through—1500 words is not. If you’re not writing for humans, then you’re writing for spam filters… so make sure you keep your email paragraphs short, sweet and to the point.

But that doesn’t mean they have to be boring! Don’t be afraid to be personable in your email, use friendly language and don’t always go for the hard sell (however tempting it may be).

Learn more about how to write effective emails here.

5. Proof before you send

A typo here and there may be harmless, but an email with too many spelling errors can flag the spam filter. In fact, in the same Radicati Group study they found 80% of all respondents noted spelling and grammatical errors as the most unacceptable email offense.

So it turns out people really do care about spelling and grammar—so make sure you always give your emails a proofread before you hit ‘send’.

6. Find your frequency sweet spot

No one likes to receive 10 emails from the same company in one week. It feels pesky, like a fly that won’t stop buzzing around your face. It’s tolerable to a point, then suddenly you’re furiously swatting at the air.

Our advice—don’t be the fly. Not only will sending too many emails be annoying to your recipients (and make them more likely to mark you as spam), but you’re also much more likely to be automatically moved to spam, too. Especially if you continue to send to unengaged contacts (see point 3).  

For every industry and business, there’s a frequency sweet spot. And you probably won’t know what that is for your particular business until you start sending emails. Here’s a quick table (sourced from The Seventh Sense) of industry-specific email frequencies, which may give you a starting point:

Industry Email Frequency
Agriculture / Mining 3 per month
Manufacturing 3.8 per month
Real Estate & Construction 6.8 per month
Transportation & Storage 7.3 per month

So there you have it; a few best-practice tips for avoiding the spam filter. Basically, put your recipients first and you’re more likely to keep hitting their inbox.

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