Email Subject Line Capitalization: Types, Tools & More

ByMashkoor Alam


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Subject lines are your best bet for a good first impression and getting noticed in a crowded inbox. One way to ensure they stand out is by choosing the right capitalization style. How you do email subject line capitalization can significantly impact whether your email gets noticed, opened or redirected to the spam folder. The availability of various types of email subject line capitalization might be confusing. In this article, we decode different capitalization styles and help you make the right decision.

Table of contents

Types of email subject line capitalization

Each capitalization style has its own set of rules and conveys a different tone and formality. Let's explore some of the most popular ones.

1. Title case

In the title case, the first letter of each major word in a sentence is capitalized. Major words include nouns, verbs, adjectives, adverbs, and pronouns. Articles, conjunctions, and prepositions are typically not capitalized only if they are the first word in the title. For example: "The Sun Is Shining Brightly in New York City."

2. Sentence case

This is the most common capitalization style. In a sentence case, only the first letter of the first word in a sentence is capitalized, along with any proper nouns (names of specific people, places, or things). For example: "The Sun is shining brightly in New York city."

3. NY Times style

The New York Times style capitalizes the first letter of all words except articles, conjunctions, and prepositions, resulting in a clean and professional appearance.

4. AMA style

The American Medical Association style is used primarily in medical and scientific writing. It follows sentence case for titles, capitalizes the first word of the title, and proper nouns and adjectives. It uses lowercase for articles, conjunctions, and prepositions.

5. AP style

Associated Press style follows specific guidelines for capitalization, often used in journalism to ensure uniformity across articles. It capitalizes the first word of the title, proper nouns and adjectives, and major words. It does not capitalize articles, conjunctions, or prepositions unless they are the first or last word. It uses lowercase for coordinating conjunctions and common nouns.

6. APA style

American Psychological Association style maintains consistency in capitalization to improve readability and comprehension in academic writing.

7. Chicago style

Chicago style follows sentence case for titles and capitalizes the first word of the title, proper nouns, adjectives, and titles. It uses lowercase for articles, conjunctions, and prepositions.

8. Bluebook style

Bluebook style varies based on legal citations and generally uses sentence cases for titles. It capitalizes the first word of the title, proper nouns, and titles.

9. MLA style

MLA style follows sentence case for titles and capitalizes the first word of the titles, proper nouns, adjectives, and titles. It uses lowercase for articles, conjunctions, and prepositions.

10. Wikipedia style

Wikipedia's style guide focuses on clarity and consistency, capitalizing the first letter of the title and proper nouns.

Should email subject lines have capitalization?

Using capitalization in your email subject lines isn’t a compulsion. It is also very subjective and depends on various factors, like your audience, the context of the email, and your brand image.

However, it cannot be denied that it gives your emails and brand a good look. It also allows you to do more with your subject lines since it is the first impression of your email. For instance, you can use a word in all caps to draw immediate attention to it.

Why is email subject line capitalization important?

While it may not sound like much, experienced marketers emphasise subject line capitalization. Let’s look at some reasons behind it.

1. It proves consistency and commitment

Maintaining a consistent capitalization style across your email subject lines reflects professionalism and attention to detail. It makes your emails look well-organized and thoughtfully composed.

2. It builds a brand identity

The capitalization style you choose should align with your brand's identity. For instance, a playful and informal brand might opt for a sentence case, while a corporate entity may prefer a title case for a more polished appearance.

3. It indicates the tone of your emails

Capitalization can also convey the tone and formality of your message. Adhering to a more traditional style like title case or Chicago style for important business correspondences can convey a sense of seriousness. In contrast, a casual and friendly email might employ sentence case or even NY Times style.

What are the different capitalization tools?

There are many tools that can help you capitalize your email subject lines instantly, like Capitalize My Title, Title Case Converter, and TextFixer.

OpenHigher AI, an AI subject Line Generator by Mailmodo, helps you pick your preferred email subject line capitalization style along with other specifics you’d like to define to get more accurate and usable AI-generated subject lines.

An image showing the different capitalization styles in Mailmodo's AI subject line generator


Writing perfect subject lines and maintaining a consistent style of email subject lines is easier said than done. However, there is abundant availability of tools that can capitalize your subject lines in an instant. Using AI subject line generators like the one offered by Mailmodo is also a great idea. Even if the results are not readily usable, they provide enough inspiration to get your creative ball rolling.

What you should do next

Hey there, thanks for reading till the end. Here are 3 ways we can help you grow your business:

  1. Talk to an email expert. Need someone to take your email marketing to the next level? Mailmodo’s experts are here for you. Schedule a 30-minute email consultation. Don’t worry, it’s on the house. Book a meet here.

  2. Send emails that bring higher conversions. Mailmodo is an ESP that helps you to create and send app-like interactive emails with forms, carts, calendars, games, and other widgets for higher conversions. Get started for free.

  3. Get smarter with our email resources. Explore all our knowledge base here and learn about email marketing, marketing strategies, best practices, growth hacks, case studies, templates, and more. Access guides here.


It isn’t a compulsion to capitalize a subject line, but doing so is good. It helps your emails to stand out in a recipient’s inbox and makes them look more professional.

It's generally advisable to maintain consistency within a single subject line. Mixing capitalization styles may confuse the reader and diminish the impact of your message.

No, not all style guides provide specific recommendations for email subject lines. However, it's essential to maintain consistency with your chosen style throughout your communications.

What should you do next?

Thanks for reading till the end. Here are 3 ways we can help you grow your business:


Get smarter with our email resources

Explore our email marketing guides, ebooks and other resources to master email marketing.


Do better email marketing with Mailmodo

Send app-like interactive emails with forms, carts, calendars, games, etc. to boost email ROI.


Talk to an email expert

Get a 30-min. free email consultation with a Mailmodo expert to optimize your email marketing.

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