6 tips to avoid Ending Up in the Spam Folder

no acabar en la carpeta de spam

Spam filters are one of every marketer’s worst nightmares. Approximately 25% of legitimate emails are sent to the spam folder by email services.

There’s no magic solution to this problem. The only way to avoid spam filters is to understand what they are and how they work.

What is spam?

The terms junk mail and spam message refer to unrequested, unwanted and/or mass emails sent to bought mailing lists. The word spam is an abbreviation for “spiced ham”, a canned meat product sold by US manufacturer Hormel Foods. During World War II, it was used to feed British and Soviet soldiers.

Comedy group Monty Python made fun of it in a famous comedy sketch, which ensured the term would go down in history: four Vikings are reading a menu with lots of different dishes, but all of them contain SPAM, and they start shouting out the word: “Wonderful SPAM!” From there, its use emerged in computing, for junk emails, through the association with something available in abundance that no one wants.

How do spam filters work?

Spam filters use a long list of criteria to determine whether or not an email is spam.

Some criteria carry more weight than others. Each criterion is assigned a number of “points” and this will decide whether or not your email gets through the filters applied.

Every email service uses its own criteria, which means an email that gets into some inboxes, may not make it into others. Spam email filters are continuously updated depending on user activities like, for instance, marking emails they receive as undesired.

One of the many criteria is searching for words typically used by spammers, such as free, buy now, urgent and win money.

Use common sense and think about the words that automatically raise the red flag when you get junk email. Try not to use these phrases and words because even though your message may be legitimate, the filters will label you as a spammer and your messages will not make it to your target.

The contents of your campaign is fundamental. They must be clear, clean and attractive. Avoid loud colours, such as text in bright red or green. Make sure all your links are working. Don’t take it too far with exclamation marks and avoid overusing capital letters.

And here they are… 6 six tips for avoiding Spam Email.


  1. Trigger words 
    As mentioned earlier, there are some words you should avoid because they trigger the alarm. Some of these are: free, gift, replay, call free, investment, better price, 50% less, save up to, special offer, for only, discount, sales, deal, compare prices, get out of debt, lower price, lower interest rate, save, why pay more, buy, buy direct, we accept credit cards, click here, win money, extra income, loan, financing, increase sales, marvellous, amazing, incredible, surprising, urgent, now, do it now, call now, register now, take advantage today, you can’t live without, do it today, instant access, start today, once in a lifetime, what are you waiting for, for a limited time, priority mail, no risk, no catch, no hidden costs, 100% satisfied, as seen on TV, confidentiality, guarantee, safe, join millions of people, in accordance with the law, satisfaction guaranteed, this is not spam, for you, dear friend, greetings, congratulations, you have been chosen, you have won, sex, hot, enlargement, meet single men, single women, online pharmacy, Viagra, medicine, herbs, lose weight, be your own boss, work from home, etc.
  2. Subject
    Don’t waffle! Long subject lines with unconnected words will be your ticket straight to the spam folder. Subject lines that contain between 6 and 10 words are the ones with the highest opening rate. Don’t forget about mobiles! Be brief, concise and generate interest. Not easy, is it? Something else to bear in mind is to avoid being overly enthusiastic!!!! Overusing punctuation marks and/or CAPITAL LETTERS will put you on the radar of all email filters. Take time to draft the subject line because no less than 80% of email openings will depend on it.
  3. Metadata 
    Always remember to fill in the Alt Text or Alternative Text of your images. If the email service blocks your images, or your recipient has this configured by default, the alternative text is what will occupy the place of these images. Try to be creative and attract attention. If the image was the one from this article, for instance, don’t call it “cans of meat”. Instead, try to generate interest with the name and invite your users to unblock the image: “the word spam explained”. In this example, not only do you attract attention to your description, but you also stir interest. Spam filters also check email metadata, whether or not you are already in the recipient’s contact list and if you use anonymous and free email addresses like, for instance, Gmail or Hotmail. Try to use an email attached to your private domain, e.g. newsletter@nombredemiempresa.com.
  4. Your IP address
    Some filters will label your campaigns as spam if someone else has sent spam from the same IP address. This is why we take complying with our conditions of use and anti-spam policy very seriously. When you send out a campaign, you do it through our servers. Our reputation is very important and this is why we not only comply with all regulations, but it is crucial that you also do this..
  5. HTML
    Dirty code, too many tags and sentences pasted from a Word or Pages document can activate spam-filter alerts. Use our optimised templates or work with a specialist designer.
  6. Image / Text balance
    Our last tip, and perhaps one of the most important, is to respect the ratio between image and text. Don’t create an HTML that is basically a large image with no, or almost no, text. Spam filters can’t read images, so they’ll assume you’re trying to fool them. Respect the 50:50 balance between text and image, but the more text the better! And, of course, optimise the size of your images. Some editing software will allow you to save a website version of your image, which significantly reduces its size, without losing quality. Try not to exceed 100 KB with images.

Other issues you should take into account are:

Avoid using the word “test” in the subject line. When you send tests to your customers for approval, avoid this type of word. Instead, send tests with the subject line you plan to use.

Don’t be annoying! Sending too many campaigns can cause your recipients to get fed up with you. There is no exact formula for knowing how many communications you should send, since it all depends on your sector. However, generally speaking, sending more than two campaigns per week may lead you to be considered a spammer, unless it’s clear that you’re a communications company, like a magazine or newspaper. If you’re a fashion firm, sending more than one email campaign per week may not be a very good idea.

To find out if you have a spam problem, visit your statistics section to analyse your results. If you see you have a lot of people who have signed up to your blacklist or that your opening ratio has significantly decreased over time, it might be worth making sure you’re following the guidelines properly.

You may be reported as a spammer even if you aren’t one. Sometimes, instead of cancelling their subscription to a mailing list, users mark the email as spam, to avoid receiving more emails. There’s nothing you can do to avoid this, particularly because it isn’t your fault. Being marked as a spammer is serious and this is why it’s extremely important to send emails to recipients who want to receive them.

Remember that complying with spam laws affects your results and the efficiency of your campaigns.  If you have any further doubts, see our anti­spam policy.

Spam should be taken very seriously. Comply with anti-spam regulations, use a clean list and take care over the appearance of your communications.

Follow these simple guidelines to make sure your message makes it to a safe harbour.