25 Best Practices for Email Subject Lines That Work

Every marketer wants more open rates and clickthroughs, getting them is another matter. Email marketing is an entire specialty unto itself. One thing we must keep in mind that it is very hard to please people these days. Even if they happily subscribed to your newsletters or any other email subscription, one day they might report your email as spam, or just unsubscribe from your list, or simply ignore it. Reason? It didn’t tempt your reader to open the email. How did they decide not to open it? Just by looking at the subject line. 

The subject line is like the ‘gatekeeper’. Your email subject line can prevent a reader from opening a sales email. No matter how stellar your email content is, no one gets to read them if they aren’t interested enough to open your email in the first place.

So, how do you write a great email subject line? It all comes down to a few best practices that you should apply to both the subject line of your message and the message body itself. 

Read on for our rundown of 25 best practices for effective email subject lines to get the most out of your email campaign. 

• There's no such thing as a perfect email subject line - The best way to understand what makes some email subject lines more or less effective is to study what works for others and then try it for yourself
• Keep your audience (and your goals) in mind - An email subject line should be such that it makes your reader curious, so your reader cannot help himself and should open and read the email urgently. The success of your campaign depends on how well you maintain the interest of your subscribers over time and this will happen only if you know your audience well.
• Localize - Collecting (and using) geolocation information can improve open rates by being personal and relevant. 
• Personalize email subject line - We may never find a definite answer what is good and what is bad with regards to the personalized subject line. But, according to the Science of Email Marketing, emails that included the first name of the recipient in their subject line had higher clickthrough rates than emails that did not.
• Customize subject lines - Customizing email subject lines will drive more attention to your emails. We understand that it's not possible to customize subject lines for each individual who receives your email, you can segment your audience into multiple groups so you can target each group or list separately.
• Optimize for mobile - According to Litmus, nearly half of emails are being opened on smartphones and tablets – that’s a 500% increase in just four years. Mobile email apps display approximately 35 characters of a subject line in the inbox view. Anything more than that will be getting cut off. To prior to optimizing your email subject line for Mobile devices, analyze how many of your emails get opened on smartphones and tablets.
• Use logical keywords for search and filtering - Most people set up filters and folders to manage the clutter in their inboxes. So it important to include related keywords in your subject lines to make email searchable.
• Keep your email subject line concise / keep it short - The best email subject lines tend to be either really short (or really long). There’s a large correlation between the campaigns with the highest Open Rates being within 30-40 characters. Subject to the condition that these are bold, self-contained declarative statements. Get to the point quickly, and focus 100% on the major pain or benefit your campaign provides.
• Simple, no-nonsense email subject lines - People have short attention spans. So, don’t make them work too hard to understand your subject line. Use clear language and keep it short while cutting out any unnecessary words.
• Convery sense of urgency or other scarcity tactics in subject lines - Craft your subject lines to establish a personal connect and it can make your recipients feel special. Right phrasing can get the readers open your emails and the effect can be magical. 
• Offer value
• Use vivid words that evoke emotion - The best subject lines are the ones which evoke an emotion. This emotion simply connects with your reader. The task is to find and get to the point with bold, powerful statements that instantly resonate with a person’s primal motivators and top-of-mind pain point.
• Use numbers or lists - Using data and numbers is an effective email marketing best practice. It is also a great way to get your emails noticed. Who doesn't like simplifying things? That's what lists do for us. Lists help break complicated concepts through a series of smaller parts. 
• Ask compelling and engaging questions - A question in your subject line inadvertently creates a call-to-action. Your recipients are more likely to open the email to get the answer, or simply gain a better understanding of why you’re asking.
• Be unique - We just love unique things, don't we? A unique information for your customer is what your business can offer them that they can’t get anywhere else.
• Consider symbols/emojis in subject lines but don't overuse it
• Test your subject lines - Your email subject line is one of the single easiest elements to test in your email campaign. Tests can help you see how your email subject lines will look across devices, as well as how they compare to shorter or longer versions. Send test emails to see how subject lines render on all devices. This will help ensure that your subject line reads well wherever it’s sent.
• Give the user an idea of what is in the email - It should be clear to your reader as what will they get out of this (make it beneficial for them ultimately). They must have an idea as to what does your email contain.
• Consider the 'from name' (Company or Individual) - The 'from name' can be as important as the subject line itself because subscribers won’t open emails from people they don’t recognize. Use the 'from name' strategically to say who you are as the sender, and keep it consistent over time.
• Use groups and segments for your list - Segmenting your readers into groups or lists helps you target better. Sending information that’s relevant to them becomes easy. 
• DON’T WRITE IN ALL CAPS - A subject line written in all CAPS is not going to get you an email open. Your message may not be conveyed well. It is like yelling at people and people certainly don't like it. 
• Don’t use spammy words - Avoid loud punctuation marks & symbols. Words like ‘free’, ‘guaranteed’ etc. won’t help you either. Don't use all CAPS and take out words that trigger spam filters.
• Make your subject line relevant to the message.
• Use a unique subject line for every email - Make sure you change up your subject lines. Don’t reuse the same subject every week or month. You want your recipients to know that you have fresh relevant content that they simply must read!
• Compelling Call to Action - Use CTAs in your subject lines to provoke an immediate response from your readers. CTAs also create a sense of urgency and it can be a powerful tool for increasing open rates and user engagement.