What not everyone knows is what faults may be causing some recipients to simply ignore them.

The subject line is as much a determining factor in the success or failure of your email marketing campaigns as is the good management of your contact list to ensure deliverability and define the content.

Unfortunately, too many companies continue to make amateur mistakes that cause significant drops in their open rates.

To help you reverse that trend, here are four subject line mistakes that some of our clients frequently make, and that you should avoid at all costs.

Mistake No. 1: Very long issues

If we've learned anything from Twitter and Instagram, it's that people are constantly on the move and their attention spans are increasingly fleeting.

Email campaign subject lines of up to 15 characters yield the highest open rates. Add to this the fact that most phone screens only display between 4 and 7 words.

This scenario presents us with a challenge: to be able to say more in as little space as possible and still make a good impression.

Make sure that the subject of your messages is always brief and attractive. Studies on this subject suggest never exceeding 50 characters, which is enough to capture the recipient's attention and prevent them from deleting your messages.

While this represents a great challenge, it is also an opportunity to develop creativity with phrases that truly stand out in your contacts' spam-filled inboxes.

      Mistake #2: Focusing on yourself and not on the audience.

In its early days, email was a way to instantly connect with friends and loved ones over the Internet, but things have changed.

Today, it is more likely that the vast majority of the messages that fill your contacts' inboxes are spam from companies that want to sell them something by highlighting a good offer of their products or services (focusing on them). In other words, it's a lot of noise and not messages from a friend or someone the recipient knows.

To avoid being just another noise generator with offers and promotions focused on your company, what you should do is just the opposite: focus on your audience, offering concrete benefits that your contacts value.

People won't mind hearing your big news, they want to know what's in it for them. So make sure your subject line is aimed directly at your contacts' interests, their needs, tastes and choices. Tell them exactly what they're going to get out of clicking that opens your message.

An easy way to do this is to replace all the expressions "we" and "our" with "you" and "your".

Some examples:

• Thank you for downloading our eBook → Here is your free eBook!
• Get to know our most important features → Accelerate your sales with these new features!
• We have great news. → You will love this great news.

Also, segment your contact base to personalize your messages. Use key data that reflects the interests of your audience to craft your subject lines. This will help make them more relevant to your audience and, in turn, increase the likelihood of clicks.

Mistake #3: Not testing

When you are developing a very important email marketing campaign for your company, the last thing you want is to lose your audience by using an inappropriate subject line.

You need to make sure that the subject line is the right one, that it offers the best possible results, but many marketers overlook its importance and end up launching a meaningless or poorly focused text, written just 5 minutes before scheduling the mailing.

To correct this error, we advise you not to blindly obey the status quo. Even if you have successfully applied a dozen of the best business practices, don't forget that each person or audience group is different and may react very differently to the same sentence.

Create your own best practices and then apply them. Listen to feedback, only then write. Heed the advice of experts and then put it to the test.

Best practices, as well as ideas contributed by your peers, should be just the basis for starting your analysis. When starting an email marketing campaign, brainstorm with your team to determine both the message itself and possible subject lines.

When you're done, test them. With this data in hand, you will be able to move confidently towards the success of your campaign while minimizing risk. Just as without risk there is no reward, with a well-calculated risk your reward will be much greater.

       Mistake #4: Wanting to be all-encompassing

In essence, a subject line should grab attention. It was designed to be a brief preview of the message inside. We insist: brief preview.

Many marketers don't want to leave anything out and include the entire campaign in that piece of text.

Regarding the expression "why buy the cow if you can get the milk for free?", we wonder: why would a reader open your message if he has already got all the information? That is, if the subject line already contains everything they need to know, what motivation would they have to click and open your message?

This error can be corrected by triggering the recipient's curiosity in the subject line.

In other words, it provides enough information in the subject line to capture the reader's interest, but omits what is necessary to compel the reader to open the message to satisfy his curiosity.

Some examples:

• Trend guide for this winter
• You are missing the best part of our magazine
• When is the best time to be creative?
• If she did it, why not you?

Take note of the importance of the subject lines and avoid making mistakes in them so that your messages are opened in the first place. Only then will your campaigns be able to meet the business objectives for which they were designed.