If you are doing email marketing you know that one of the major concern is to overcome spam filters, spam traps, and anti-spam laws.

Indeed the ISP (internet service provider) is doing everything to fight against spammers however marketers like us get collateral damage and struggle to reach the recipient’s inbox. A research conducted by ReturnPath reveal only 80% of email sent to reach the inboxes. How is possible? Well, there are many reasons but it surely does make an impact on the sender's reputation and email deliverability.



The first ISP’s barrier to fight against spammers is spam traps that are email addresses specially designed for tracking spammers.

Spam traps are inactive emails addresses that IPS after a certain inactivity period. The consequences for sending an email to these address are not very important. Your ESP will send you a bounce notification to let you know you’re sending emails to inactive email addresses, however, if you keep sending emails to hard bounces the ISP will maybe put you as a SPAM sender.

The second ISP’s barrier against spammer is spam filters. This is a program that prevents emails reaching inboxes by implementing different criteria such as unsolicited bulk mail and unwanted mail. Spam Traps analyst precisely your emails so be sure to write relevant and good content to reach the subscribers.



Here are the things that you should know to avoid Spam

Be aware of the technicalities

Be on the know with the technical issues of email marketing in order to improve your email deliverability.

Use identifiable sender name

It’s always good practice to send your emails from an email address that includes your name with your brand name to let the recipients identify you. The reason is simple, people prefer open email which contains the personal name in the ''from'' field compared to the generic name. it will increase your open rate of 12%.  

The spam technologies will analyze information about where is from your email by scrutinizing IP address and domain. Also, we advise you to not change often your IP address source otherwise the ESP will be alert and check on you. Finally don’t change your email address regularly in order not confuse your recipients that may mark you as spam.



Choose a good ESP

Here in Taximail, we have gained a good reputation by letting our customers sending only valuable and relevant content to get high scores on their IP addresses. You can take advantage of the spam diagnosis to be 100% sure that your email deliverability is checked before sending your email campaign out.

Third-party certificate

You can be guaranteed from an ISP that you are not a spammer by getting an accreditation of sender. Some companies certify you as a trusted sender. This certificate may guarantee you to reach plenty of inboxes however this is not a free service but your you conversions could be positively impacted.

Check out if you’re blacklisted

Your email deliverability can be affected if your IP address has a bad reputation. So you’ll be more likely to land in the spam folder.

Some tools are available to check if you’re blacklisted such as Multirbl.Valli or MxToolbox




Keep your email list clean


It’s crucial to keep your email list clean to avoid spam filters and spam traps.

Never buy email lists!

Firstly this is illegal to transfer or selling email addresses to other lists. You’re also a violating the ISP terms and service and the people’s privacy who never want to be contacted by you.

Mostly these emails lists have 10% up of unknown email addresses and 44% of emails addresses are from ISPs. This email list includes data that are not updated, inactive emails addresses and spam traps.

Take out the hard bounces from your list

As previously explained, if you keep sending emails to an inactive email address you’ll probably be marked as a spammer. The ISPs track the bounces rates to determine your sender reputation, indeed your email deliverability will be affected by a bad reputation.

Be aware when you receive the bounce ISP notification and delete the email address from your email list.


Be careful with the inactive subscribers

If you notice that subscribers are not reading, opening and clicking your emails you should take action.

It will affect your company domain’s reputation and your email deliverability. A simple solution could be to re-launching an engagement campaign or manually unsubscribing them if you don’t hear from them.

Double opt-in and contact list

An easy way to make sure your subscribers want to hear from you is to send them a second email where they can confirm they want to receive emails from you.

This subscription process will help you to keep your list clean and ensure your reputation.

By asking your subscriber to add you to their contact list, you’ll avoid easier spam filters. Indeed if subscribers add you to their contact list, it warns to the ISP that your IP address is okay and he wants to receive your emails.



Mind your subject line

70% of the recipients will mark as a spammer only by reading Email Subject Line. This is an important point to bypass the spam engines.

Don't yell at people

In general communication, it seems to be disrespectful and rude when we’re using capital letters. Most of the people prefer lower case in subject line. The spam filter will be alerted by subject line written in upper case same as the receivers who might mark your email as spam.

Also, don’t create a wrong impression by using plenty of exclamation points in your subject line. The research shows that subject line that ends with a question mark get better open rates than the ones that end with exclamation points.

Don’t use spammy words

Be careful with the wording of your subject lines. Some phrases and words such as ‘’cash’’, ‘’best price’’, ‘’free’’, “ฟรี”, “เชิญ”, “รับ” are already blacklisted. Avoid these words and care your subject for passing through spam filters

Don’t promise fake things

It’s important to write your subject line according to your offer in the email in order to avoid being marked as spam. People will probably mark you as spam if your content doesn’t correspond to the subject line offer.



Check your email body

The ISP rigorously analyze your content as well. Care about the design the attachments, the fonts, the images and everything in your copy. The solution is to keep minimum details and simplify everything.

Stay away from rich media content

Most of the email clients don’t let you view rich media content such as video or flash content, so don’t put them in your emails. Indeed if you use them and they don’t work properly your email might be considered as spam.

if this kind of content is essential for your email marketing campaign preferred to put it on your website and you can insert an image with a play button then redirected them directly to your website video.

Don’t use Javascript and other dynamic content as they can alert spam filters as well

Stay away from embedding forms

Mainly the common email clients don’t support embedding forms and represent another alert for spam filters. Link to your page directly or insert a call to action if you need to include embedded forms

Stay away from including attachments

The spam filters will be alerted if you attach files to your emails such as Word or PDFs documents. By the way, the size of your email will be impacted as well so it will take longer to load. The same solution as above you can include a link or call to action to your website where you can locate your documents.

Stay away from using excessive fonts and colors

A survey revealed, over 60% of people thought inappropriate if the marketer would use irregular fonts, fonts color, and fonts sizes and 70% prefer one size fonts. Irregular sizes and fonts colors and invisible text will alert spam filters to make it easy





Include HTML and plain text as well

Take your time to build an HTML version and a plain text version of your email. The first one lets you design your email then the second allows you to be plain and simple.

Make sure your code is correct because if your email has incomplete or broken tags, the spam filters will likely block it before reaching the inboxes.



Correct grammar and spelling

Every good email marketing campaign is made with proofreading and spells checking otherwise it can affect your credibility and your subscribers might feel you are not professional.

A survey shows that 80% of the people think spelling and grammar error an important email offense.

These mistakes are also a spam triggers so take your time to check and recheck your copy before sending.

Unfortunately, there is no special formula that promises your emails will not land in spam. ESPs, ISPs and anti-spam laws are strong. In order to ensure your deliverability you just have to be aware of technical issues, stay away from spam triggers, mind your subject line and your email bodies, and abide technical issues then you will be able to protect your IP address and domain, your sender reputation, ensure your credibility from being blacklisted.


Posted by
Posted by
Boy is the head of Development team on Taximail. He manages the team of developers in building, improving and innovating Taximail to its full potential. He spends his free time outdoors with family. Also, playing PS4 is one of his favorite recreation.

Grow your business with
email marketing

Get started free