The subject line is a key door opener in email marketing and significantly decides whether or not a user will open an email. In times when emails tend to bulk up in the inbox, a subject line needs to stand out in order to activate a user. We have compiled a few dos and don’ts for you concerning the optimisation of subject lines in email marketing.


1. Get to the Point

Subject lines should be brief and concise. Firstly, to ensure visibility. Depending on the used email client, only a certain number of characters will be displayed in the inbox. The longer the subject line, the higher the risk that the text will appear cut for some users. Essential information should therefore be placed at the beginning of the subject line. Secondly, the user will need to capture the statement of the subject line at a first glimpse. The attention span is very limited. Tips on how to create short, concise subject lines can be found in this article:

2. Arouse Curiosity

First of all, we need to attract a user’s interest via the subject line. Standard subject lines such as “Newsletter 201” or “Company XY Newsletter” will make this difficult, unless the user has already learned that he will in fact find useful information behind this sender. The subject line should therefore show the user what to expect and why he should open the email. You should also clearly put the use in the foreground, e.g. with a subject line, such as, “Relax on the Island of Jersey and Save 30%”. Another option to tackle interest is the use of a question in the subject line. Special characters are also suitable to make a subject line stand out. However, special characters should be used with caution as excessive use is not only seen as a sign of spam by many users but also by spam filters.

3. Individualise

One’s own name is always an eye catcher – this also applies to subject lines. However, the effect of a personalised subject line can quickly wear off, if it is used too often, you should therefore minimise its use. Recipients whose name is not known, should always receive an alternative subject line so that they don’t experience a failed personalisation attempt. Instead of the name, other personal attributes such as the company name, city or the last purchase can also catch attention.


1. Misleading Formulations

You must avoid formulations which trigger false expectations on the content of the email, as this can lead to the user’s discontentment and can massively damage the trust and therefore customer loyalty. Furthermore, misleading formulations can also cause legal problems.

2. Use Spam Terms

Spammers often try to lure users through eye-catching subject lines, e.g. through words written entirely in upper case, inflationary use of special characters or keywords such as “free”. You should therefore use these elements in a sensible way, not only to avoid problems with spam filters but also because users will perceive them as dubious. Check each email for the risk of being caught in a spam filter. Many email marketing solutions provide the corresponding tools.

3. Give Away All Information

As mentioned above, it is the task of the subject line to arouse curiosity with users. It should give a reason for why to open the email. However, a user only opens it when the email provides relevant content which was not already visible in the subject line. A transaction email with the subject line “Your order x has been dispatched on xx.xx.xxxx and will be with you approximately on yy.yy.yyyyy” for example, already transmits all the relevant content from the email.