Understand how the spam filters work

A spam email is considered an unsolicited, irrelevant email, sent in bulk to a list of people. Spam filters are programs created and used to identify unwanted or unsolicited emails and prevent them from reaching inboxes. Major ISPs like Google and Yahoo! have built-in spam filters and filtering processes to ensure their users are protected from “junk” email.

The war between Internet Service Providers and spammers can also hurt companies and their marketing activities in the form of “false positives”. In other words, legitimate commercial emails that are mistakenly routed by spam filters to bulk folders. According to ReturnPath, about 21% of permission-based emails sent by legitimate email marketers end up in junk folders.

In reality, working in a fast-paced environment you cannot easily afford to spend time and money creating email campaigns and newsletters only to have them end up in the spam folder.

7+1 tips to avoid spam folder

Fortunately, there are some guidelines and tips to follow in order to safeguard your emails from being as spam.

Why could an email be flagged as spam

There could be many reasons why your emails got flagged, from a blocked IP addresses to the number of images. Following are the most common reasons and how to tackle them, so you can optimize your emails to perfection.

#1 Optimize your subject Line

Have a sweet email subject to attract attention: Making someone open the email is 50% of the job. It is okay to keep the subject line generic instead of over-promising which may seem too far-fetched.

Make sure your subject line is relevant to the purpose and the content of your email. Don’t try too much to create the sense of urgency or offer. A good rule of thumb by Hubspot is this: If it sounds like something a used car salesman would say, it’s probably a spam trigger word.

Don’t use “spammy”-like words or phrases, capital words, and excessive punctuation. Using them in your email can trigger a spam filter particularly if they are found in the email subject line. Check following examples of subjects that could create a spammy essence to your email:

“This is urgent!”

“Exclusive offer..”  or  “…super offer NOW!”

“Get results within 24hrs”

“Giving away….”

“Exciting news!!’

“FREE e-book”

Also, avoid deceptive subject lines or misleading claims as this is also a true spam tactic. Needless to mention that it creates a bad user experience in any way! For instance, avoid using the trick to start the subject line with “Re:” or “Fwd:” in order to suggest an ongoing communication with the sender. Since it is an automated email, it is easily recognized as not a manual, personalized response.

If you have built a relationship with the list and the recipients know who you are, then only you may take the risk of selecting some of these catchy phrases.

#2 Be careful with your body content

Spam filters analyze the email’s content. This means that you should be careful about what exactly you write. Really emphasize why this is worth their time, not yours.

The same principles with the email subject line are valid for the body content as well. Copywriting that makes people want to take action is both simple and compelling. To make your writing sound more personable and relatable, use casual language, colloquial expressions, and even personal anecdotes. Here is what to have in mind when writing your content:

  • Be careful not to use excessively your keywords. Otherwise, over-optimizing your email with keywords, can be harmful to user experience and trigger a spam filter.
  • Don’t include too many links to your landing destinations and link only to legitimate sites with reputable domains. Linking to a spammy website is a sure way to get a bad reputation.
  • Balance the image-to-text ratio. Communicating your message through one large image at the body as your entire email, or using too many images, in general, tends to end up in recipients’ spam folders. When you decide to use images on your email,  remember to host your images at credible services only.

For example, the following screenshot is part of the newsletter with offers from a shoes’ e-shop. The offers are great but actually, I never got to see them as the newsletter ended up in my spam folder. Why? Probably too many images -instead of at least of a large one with all the products- and links for all the highlighted products.

example of shoes in an eshop newsletter

  • Be short and to the point: No one is going to read a really long email. Content must be brief and straightforward. Too much copy is another red flag for spam filters.
  • Before sending the email, always make a final proofreading. Spelling mistakes aren’t just unprofessional — they’re actually a spam trigger, too.

#3 Irregular email format

Don’t try to be too creative with different formatting at each newsletter or at each section of the newsletter. A research conducted by The Radicati Group (2014) showed that over 60% of respondents considered it unacceptable for email marketers to use different font sizes, irregular fonts, and different font colors. Nearly 70% of respondents prefer fonts to be one size. Spam filters respect what the users prefer and usually flag as spam content the following: red text in the body of the email or excessive use of underlining and bolding. In addition, fonts that are too big or too small can trigger a Spam filter. The reason is that many Spammers either try to hide text in an email with tiny font sizes or they use huge font sizes to make an offer.  Use a standard font size to avoid Spam filters.

Remember to avoid using invisible text, i.e. a white font on top of a white background.  This is actually pretty serious as this is a common trick that spammers use. This is like an instant red flag for spam filters!

#4 Use a familiar sender information.

Mailbox providers evaluate more than just the sender’s IP, domain, and content. Furthermore, if subscribers fail to recognize the “From” field, they may delete the email without reading it. They may have forgotten about your brand or you may have used a different email that you usually send your emails. Doesn’t matter; if they don’t know who sent them the newsletter is really easy to ignore it.This will hurt your “open” ratio to start with. Even worse,  that had signed up to your list and generate negative feedback by marking messages as spam.

who are you?

So, try not use general emails like noreply@ / newsletter@ / marketing@. It’s much preferable to send the emails from a sender persona, for example, john@x.com. This email may belong to the real person handling the sales/business development or be a fake persona with a fake role of business development.

Kissmetrics analysts have even noticed variations in deliverability results from using the address support@yourdomain.com versus newsletter@yourdomain.com.

Once you find your preferred sender information, stick to a limited number of verified, recognizable From field names. Build a good reputation for those addresses by sending only engaging, solicited emails, and you’ll notice the difference.

#5 Keep your email lists to date & clean

It goes without saying that you should avoid purchased lists at any cost. Not only is it illegal and punishable by US law, it could also crush your email marketing program and do long-term harm to your brand. At best, your messages may end up in junk folders. At worst, you will be a spammer.

i didnt sign up for this

A very good practice is to also seek explicit consent to send each type of content (eg offers, company news, partners’ offers) so that your subscriber doesn’t mark you for spam, or even worse, report you for abuse.

Proactively remove the inactive subscribers. Before you start the process of evaluating your subscribers and remove the inactive ones, try a re-engagement campaign to regain their interest. You could offer a special offer, a “we missed you” message or “are you still interested in…?” email in order to recapture their attention. If that doesn’t work, simply ask them if they wish to remain on your list and include an easy way for them to opt out. I know that this hurts a creator as hell to ask his list to unfollow him if not interested anymore, but it is for the greater good of his brand. If the subscriber remains inactive, remove them from your list.

#6 Use double opt-in to your newsletter list.

Single Opt-In vs. Double Opt-In - the main differences

The “double opt-in” process includes two steps. In step 1, a potential subscriber fills out and submits your online signup form. In step 2, they’ll receive a confirmation email and click a link to verify their email. Then only the email gets to your list. “Single opt-in” means a sign-up process in which a user does not need to confirm that he or she signed up.

Using single opt-in option may cause greater risk to your sender reputation. When you don’t use a double opt-in system, a number of bad addresses can enter into your email list. The double opt-in process eliminates many of the “bad” email addresses, for instance, emails with typos or unreal email addresses. Mistyped email addresses can impact your sender reputation by adding to the statistics of undeliverable addresses that you’re attempting to mail to.

The double opt-in protects against instances where somebody may be using emails that he doesn’t own (his friends, family or not) and add them to his mailing lists without approval. Then, when the real owner of that email address receives your email, chances are that he won’t recognize you and he may mark you as spam. This will negatively impact your sender reputation.

#7 Ιnclude a clear unsubscribe link and a physical mailing address

This has happened to me a lot and cannot be a coincidence. Have you got a promotional email but cannot see where to unsubscribe? To make your recipient’s life easier, just make unsubscribing easy and straightforward. Include an unsubscribe link in the footer of your email and let the link stay live for at least 30 days after sending. Since you give your recipients the option, of course, remember to honor the unsubscribes. This means: Remove unsubscribes instantly or within 10 days of opt-out.  Or use a platform like Mailchimp or ExpressPigeon that take care this for you!

Even if the recipient has opted-in, he/she may not be interested anymore or may forget to sign up for your list. In case that there’s an unsubscribe button clearly visible, they can just click on it and remove themselves from the database instantly.If they can’t find an unsubscribe button they’ll mark the message as spam or junk, which can have undesirable consequences for the sender.

Just let them go!

#8 Whitelist your domain

When confirming your new subscribers (e.g. via a welcome email), ask them to add your “From” address to their address books. It is a foolproof way to release all future emails from the constraints of the spam filters. This is so easy and has really good results, yet brands don’t practice it regularly.

Before you go

Managing to get past spam filters while sending a suspicious message is a complicated process. Nevertheless, in reality, all come down to sending useful email to an interested audience using a reputable email service provider.  Doing your best and creating top content in order to advance your marketing tactics and succeed.

best newsletter

Needless to say that email marketing is constantly evolving. As a result, my advice is: stay in the know and get constantly educated on best tips! This will ensure you’re always following best practices – and the law. You should stay up-to-date on changes in email sending laws, ISP behavior, and spam filter technology.