The 12 Worst Mistakes People Make In Email Subject Lines

Writers Write is a resource for writers. To help you improve your writing, we’ve written about the worst mistakes people make in email subject lines.

Knowing how to write brief descriptive subject lines is an important part of email etiquette. Your subject line is the most powerful tool you have to tempt readers to look at your email.

Readers will delete your email if you are too vague, repetitive, eager, cryptic, wordy, or unsure.

TOP TIP: If you want to write great emails, buy The Complete Email Workbook.

What are the 12 worst mistakes people make in email subject lines?

  1. Not writing one. Your email will be blocked by most spam filters if you don’t include a subject line. The recipient will not even read what you have written. If it does make it through the filter, an email with a blank subject line is more likely to be deleted, or lost in a busy inbox. It will also annoy the recipient, who has to open the email in order to see what it’s about.
  2. ALL CAPS. Why would you even think of writing this way? It is the equivalent of yelling in someone’s face. I delete any unsolicited email with ALL CAPS in the subject line. It shows me that the sender has no email etiquette and is inexperienced in a digital world.
  3. Cryptic clues. Unless you are mailing the members of a mystery club, this is a bad idea. Don’t include rhetorical questions, quotations or clues. Keep your subject line relevant, clear, obvious and simple.
  4. Symbolic gestures. Do not include currency, (too many) numbers, or symbols in your subject line. This looks like a sales pitch, even if it isn’t one. Your email will probably be relegated to the spam folder.
  5. Spelling or grammar errors. Making mistakes in your subject line makes you look unprofessional. A subject line is a calling card and if you can’t be bothered about appearances, don’t expect a response. Spell check the subject line of your email. Your customers will wonder how competent you are if you can’t get this right.
  6. Overwriting. In 2012, the McKinsey Global Institute said that workers spend about 28% of their workday reading and responding to emails. This figure continues to grow at a rate of 4% every year. This means it is more important than ever to keep your subject line brief. Long-winded, wordy, irrelevant subject lines annoy readers. As a rule, email subject lines should be no longer than 50 characters of relevant information.
  7. What happens in vagueness… The subject line should communicate the content and purpose of the email. This allows the reader to decide on its importance without having to open it. Don’t use one-word subject lines or longer subject lines that fail to convey your intent. Making a customer guess is ridiculous. Keep it simple and straightforward.
  8. Spam keywords.  Avoid using spam keywords such as free, money, cut-rate, offer, gift, and deal. You are not writing an advert. Even if the spam filter allows the email through, these pushy tactics will annoy the reader. Most people do not want the equivalent of a billboard in their inboxes.
  9. Not linked to content. Does the text in your subject line have anything to do with your email? Does the email contain the information you promised in the subject line? Readers who open the email but do not see what they are expecting to see become more annoyed than those who simply delete emails that do not interest them. You have wasted their time and broken your promise.
  10. Not revealing referral details or urgency. If the email is important, tell the reader. You could say ‘Stock Shortage – Urgent Response Required’ or ‘Powerboat Launch – RSVP by 20 May’. If you are sending the email because a mutual friend or acquaintance has referred you, mention it in the subject line. Say ‘Fred Draper Suggested I Apply for Sales Position’
  11. Begging is a bad idea. Do not beg in the subject line. It makes people uncomfortable and it makes you look desperate. Your unsolicited email will be so unappealing that it will be deleted.
  12. Repeating yourself. Avoid using repetitive subject lines. If you email a group of people regularly, make sure that your subject lines are not exactly the same. Find simple, clever ways to say the same thing.


  1. If you want to write great emails, buy The Complete Email Workbook.
  2. If you want to improve your business writing, buy The Complete Grammar Workbook.
  3. Buy The Report Writing Workbook if you need help writing reports and proposals.

by Amanda Patterson

© Amanda Patterson

If you enjoyed this post, you may want to read:

  1. How Five Annoying Email Habits Would Appear In Real Life
  2. The One Essential Email Trick Every Business Writer Should Know
  3. The Top Seven Tips for Writing Emails
Posted on: 9th February 2015

4 thoughts on “The 12 Worst Mistakes People Make In Email Subject Lines”

  1. I actually disagree with your item 12. We have reports which have to be run before a meeting every week and have an email rule that all emails with the same subject line are automatically added into a specific folder. If the group start changing the subject line, it doesn’t go into the correct folder and just messes up my inbox, so if you send regular emails to the same group of people with regular updates of similar information on, please do try to use the same subject line each time as it makes life a lot easier when we’ve over 465 emails to deal with!

  2. Treva O. Wilson

    Your tips are very professional, and will I’m sure make a significant difference in our future emails. Thank you.

Comments are closed.