1. Use Capitals the right way
On of the biggest issues with email marketing subject lines is that it can often be wrongfully read by email service providers as,
spam- any brand's biggest nightmare. One of the red flags for spam detectors along with an overuse of exclamation marks and words such as "free" is capital letters in subject lines. Going nuts on Caps Lock will seem like a way to grab attention, but you could be grabbing the attention of the spam filter. The key here is to use capital letters in a consistent way, for instance only writing the name of your brand in capital letters. The message here is clear: use with caution and so in a consistent manner.
2. Underplay it
If using big, bold capital letters and exclamations are the loud way of communicating your marketing message to your customers - what would be the quiet way? The answer is phrasing your subject line in a way that makes it sound like a secret or an underground event. By underplaying importance you could actually gain more attention and tempt more subscribers to have a look.
3. Digits
Numbers rule our world in many ways and research has shown that people are immediately attracted to numbers in a textual context such as subject lines. However, just using a percentile when referring to a sale or merely listing a price, is a bit boring. Think of how you can use a number as a short hand or even as a joke or a saying. Some fun examples could be something like: "3...2...1 Go" or "4 dresses, 4 real". The idea is to be original and to grab attention without being tasteless.
4. Make a promise
This might seem like a boring way to communicate with customers, but it is one of the most successful ways of getting subscribers to read your emails. Be specific and clear, without being crude or too straightforward - basically tell your subscribers exactly what they can expect to find in thwe mailer you've sent them.
5. Say it with style
This one's more of a gamble, since it is not being entirely clear, but rather reliant on the fact that you have clever subscribers with a sense f humour. This will include writing subject lines that consist of wordplay, puns or even riddles.