This article is a summary on How to Write Email Subject Lines. Here are some Do’s and Don’ts.


Do’s

1. Short! Fewer than 10 words is a must; 50 characters or less. 2 or 3 words are probably ideal.

2. With clear, direct and useful information.

3. Create a sense of urgency, call to action and timely message.

4. Brand messages. Showing your brand or company name and message purpose.

5. Keep them familiar and consistent. Start with the same words so the recipients recognize you.

6. Putting a question mark after a simple statement is effective too. Something like “Discount Tickets?” will be much more effective than “Get Low-Priced Tickets While They Last.”

7. Testing. Testing. Testing.

Don’ts

1. Don’t use Selling-language like advertisements, such as “exclusive”, “free”, “opportunity”, “limited time”, “hurry” and “only”.

2. Don’t use splashy promotional phrases, CAPS, or exclamation marks in your subject lines.

3. Don’t use too many commands, such as “Get,” “Open,” “Buy,” “Save,” or “Respond.”

4. Don’t mislead your recipients with false claims, offers, or misinformation.

5. Don’t use $ symbol.

6. Don’t use “Hi” and “FYI”.

7. Don’t decide on your subject at the last minute before sending your email.

References:
15 Tips for Improved Subject Lines
19 and a Half Killer Email Subject Line Tips & Examples
Best Practices in Writing Email Subject Lines
Learn How to Write Email Subject Lines!
Five Holiday E-Mail Marketing Do’s and Don’ts
Study of Best and Worst Open Rates on MailChimp