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How to write a cold email subject

How to Write a Cold Email Subject Line

Cold Email Subject Line

Photo Credit: Lead Fuze

Why the Subject Line is so Important

The subject line of your cold email is potentially the most important part of your cold email.


Your subject line is the first part of your cold email that the recipient will see. It is similar to a first handshake or first impression.


With a well crafted subject line, your cold email is much more likely to be opened than if your subject line is too plain or too sales-y. 

How to Write a Cold Email Subject Line

Writing a cold email subject line takes a bit of skill and a touch of artistic flair. You need to be able to be enticing and to the point. When you write your cold email subject line, you should be able to address quick prompts like “who”, “what”, “when”, “where”, and “why” as long as those are applicable to the purpose of the email.

Your cold email subject lines should reflect the purpose of the email. So, it is good to have a few rough templates or ideas ready to go to use throughout your email sequence.

If you connected with someone on a social media platform, a good first subject line could be “(name) We Connected on (Platform)”. If you want to schedule a meeting with a prospect that you may not have connected with, a possible subject line for your cold email could be “How about a quick cup of coffee (name)”

If you are sending a follow-up email, you can repeat the subject line of your first cold email by adding a “re:” to the front of the subject line, or you can write up an entirely new one. Follow up cold email subject lines could be along the lines of “just checking if you caught my first email (name)” or “(name), it’s me again from (company name)”.

There are plenty of other approaches you can take to write an effective cold email subject line. Other common approaches include using humour in the subject line or a casual subject line as an approach rather than a formal approach. Many people get formal sales emails, and the subject lines can get dry or repetitive over time. By being casual or humorous, you may be more effective in your cold emails because it will break the cycle of all the regular emails that come into the inbox.

Overall, be short and sweet and aim to have a tone that breaks the normal subject line cycle. 

Another tip after writing your cold email subject lines can be to A/B split test subject lines to track what may be more effective. Not every cold email template will suit every and any cold email series. Your cold email subject line will change depending on the content of the email and the behavioural traits of your contact list.

How to Not Write a Cold Email Subject Line

Now that we have covered best practices for writing cold email subject lines, it is also noteworthy to cover what NOT to do when writing cold email subject lines.


  1. You should not have a long or wordy subject line for your cold email. Putting too much information in your subject line will often turn your recipient off, and they are likely to delete your email or just open it to unsubscribe from your email list.
  2. Don’t be overly sales-like in your subject line in a way that makes the entire email just seem like clickbait. Although many cold emails will pitch a product, service, or other CTA, a subject line that looks like you only want the conversion will cause people to send that email right to the trash.
  3. Lay off the use of filler words. You only get a few words to fill the subject line with, so avoid basic introductions or filler words and phrases like “Hey”, “So…” and others similar. You need to use your limited amount of characters wisely to write out an effective cold email subject line.


About the Author

Lydia is SendKoala’s Head of Content. Outside of SendKoala, you can finder her running, lifting, and hiking.