Should Email Subjects be Capitalized? A Guide to Proper Capitalization

Are you wondering how to create effective, eye-catching emails with proper capitalization? Are you struggling to decide between sentence case, title case, or all caps for your email subject lines? Many factors are involved when it comes to creating the perfect subject line.

In this article, we discuss the complexities of email subject capitalization and explore the benefits of each style: sentence case, title case, and all caps. We provide advice on which words to capitalize according to APA, MLA, and AP guidelines, delve into the emotions evoked by each style, and give tips for optimal customer engagement.

Explore the topics within this article to discover everything you need to know about proper email subject capitalization.

What is Email Subject Capitalization?

Email subject capitalization is the practice of deciding which words in an email subject line should and shouldn’t be capitalized. Generally, there are three common formulas for capitalization:

All capitals, sentence case, and title case.

What is Sentence Case?

Sentence case is when only the first word of a sentence is capitalized (as well as proper nouns). Using sentence case makes the subject line easier to read, more approachable, and can appear less formal. This makes it easier for recipients to quickly understand the message since only the first letter needs to be capitalized.

What is Title Case?

The title case implies that the first letter of each word is capitalized. Articles like “a,” “an,” and “the” should not be capitalized. Title case capitalization according to APA, MLA, and AP style also require you to capitalize words that enumerate or have more than three letters long. The title case makes subject lines appear more formal and polished and is often used for business emails. Using free title capitalization tools is highly recommended for accuracy.

It’s important to note that there is no one-size-fits-all rule for email subject capitalization, and you can choose what works best for your brand, who you are sending it to, and the tone of the email campaign. All that said, there are certain things to keep in mind when writing your email subject line: avoid using all caps; keep capitalized words short; avoid punctuation after the title; split words up with commas or spaces, if necessary; and make your subject line easy to read. Additionally, there is no requirement to capitalize in emails, so if you prefer not to, you don’t have to. Another thing to consider is avoiding writing everything in lowercase, as this can easily be confusing and appear unprofessional. If your company has a specific style that emails should follow, then you should adhere to their guidelines accordingly.

The next rule of thumb is to capitalize the first word after a colon and avoid ending email subject lines with punctuation marks. When it comes to capitalizing words in the content of your subject lines, the general rule is to capitalize the first word of each sentence, proper nouns, and the names of companies or organizations. Beyond that, you should generally avoid capitalizing other words, as it may confuse readers or potentially trigger spam filters. Consider splitting up the important information into different sequences, so your reader knows exactly what each message is about. Additionally, some email programs may automatically capitalize the first letter of every word, so be sure to check your program settings before sending out a campaign.

When it comes to capitalizing email subjects, the golden rule is to never write them in all caps – this fails the professional healthiness test and almost always triggers spam filters. Randomly capitalizing will make it look like a joke and also trigger spam filters – not ideal. On the other hand, sentence case email subject lines read more personal and casual than formal headline styles; they’re easier to read and comprehend than a blog or article headlines.

The following rules hold true for sentence cases: capitalize the first word of the sentence and all proper nouns. As for the smaller words, such as “i” and “you,” those do not need to be capitalized unless you want to emphasize something. Greetings, such as “hello,” and “good morning,” are typically not capitalized in a sentence. You can opt to only capitalize the first word of salutations like these.

For title case capitalization, the rules are slightly more complex, requiring a bit more care and attention. According to APA, MLA, and AP styles, the following should be capitalized: the first word, nouns, pronouns, verbs, adjectives, adverbs, and any words that are longer than three letters. Similarly, as with sentence cases, abbreviations and excessive punctuation should also be avoided. It’s preferable to keep the subject line clear, concise, and undivided, so it doesn’t get cut off by the inbox display due to length.

Using title case capitalization goes back to our earlier recommendation of using a free title capitalization tool for accuracy. Doing this ensures accuracy and keeps subject lines from triggering any spam filters. Worse yet, writing subjects in all capital letters makes it look desperate and like you’re almost screaming at the receiver, even if that might not have been the intention. Furthermore, writing all in capital letters will trigger most spam filters, pretty much guaranteeing your messages won’t reach their intended destination.

In conclusion, it’s important to consider which type of capitalization style best fits the purpose, tone, and audience of your message. Different brands may prefer either title case or sentence case, but ultimately the choice is up to you. Remember to stick to the rules you set and make sure to keep the primary message clear.

If you’re looking for a style that reads more personal and casual, sentence case capitalization is your friend. On the other hand, for more formal and professional business emails, a title case can help make your subject line appear more polished and authoritative. Above all else, just remember to remain consistent with your capitalization choices to ensure your messages are being read!

How Should You Capitalize Your Email Subject Lines?


When it comes to capitalizing email subject lines, there are a few options available. The first option is to write in all caps. Although this may appear to be the only way to have an email noticed, in fact, this style of capitalization can trigger spam filters and come across as aggressively shouting instead of courteously communicating.

This form of steep capitalization would not be suitable for business emails or other forms of formal communication.


Sentence case is the second capitalization option for email subjects. In sentence cases, only the first letter of the first word is capitalized, and the remaining words are written in lowercase letters. It may appear to be an informal form of writing, but people use this form on a regular basis for email subjects, particularly when sending messages to family or friends.

It has also become widely used in business communications due to its flexibility; it allows businesses to remain formal while still showing a certain level of courtesy and informality.


The third option available is the title case. This implies that all the words in the sentence are capitalized, except for prepositions, conjunctions, and articles (e.g., of, a, the, and, but when followed by 3+ letter long words).

When using title cases, it is important to pay attention to the length of your subject line, as it can quickly become overwhelming with so many capitals. Title cases should be used primarily for formal emails, such as those sent to customers, colleagues, or investors.

WHAT’S Right?

Choosing which capitalization style to use really depends on what effect you want to have on the recipient of your email. There is no definitive answer as to which style to use, as success will depend on many factors, such as the context, audience, message, etc. It is important to remember that some email programs will automatically capitalize the first letter of every word, so be careful to double-check the appearance of your subject line when sending.

A/B testing is the best way to determine which approach works best for your audience, as it will show which has better conversion rates.

According to one survey from 2017, out of 17 brands included, 11.5 used sentence cases in their inboxes, but there was no clear preference in several blogs from 2017 and 2021 combined.

It is important to note that in the 2021 sample, 8 out of 13 brands used sentence case, and only 3 out of 13 brands used title case exclusively. All caps were used by 1 out of 13 brands, and all lowercase letters were used by another. It seems that the trend is leaning towards sentence cases for expressing conversation and keeping subject lines clear and short.

Tips for Writing Effective Email Subjects

The key to creating effective email subject lines is like a puzzle – it requires careful thought and consideration. Crafting an eye-catching headline that will draw readers in can be tricky, but there are some accepted forms that can be used as a guide. Metaphors, similes, personification, and alliteration are all stylistic devices that can help you create an engaging subject line for your emails.

Keep it short and to the point.

A short subject line can make a big difference. Crafting the perfect subject line is essential for successful email marketing, and it should be done with care. The sweet spot for subject lines is 50 characters or less, but quality should always take precedence over quantity. Utilize rhetorical questions, short sentences, and active voice to create an effective subject line that will draw readers in.

Remind them who you are.

When you send an email, your recipient needs to know who sent it immediately – even if they are already familiar with you. That’s why adding a prefix to your email subject lines is very useful. However, don’t make this prefix too long – aim to keep it within 44 characters or less.

Prefixes might include your name, company name, blog name, or brand name. The goal is for people to recognize you easily and increase email open rates.

Know your audience, and set the tone.

It is important to get to know your audience before emails are sent. Know who they are, what kind of job they do, and how best to interact with them. You want to set the correct tone; you wouldn’t want to be overly informal when sending a business inquiry and vice versa. Depending on the person, you can add ‘please’ or ‘thank you’ into the sentence.

You can get creative with the language that you use, but make sure not to sound too corny or try too hard.

Be personable.

People are more likely to engage with emails when they are written in an interesting and engaging way. Val Geisler is a renowned email marketing expert who knows how to craft effective messages that get results.

Val works with her clients to build relationships and set expectations through the use of metaphors, rhetorical questions, and anecdotes. Her campaigns have been proven to generate impressive results, such as increased open rates, click-throughs, conversions, and more.

If you’re looking for someone who can help you create powerful emails that will drive engagement and sales, look no further than Val Geisler!

Subtle changes that make a big difference.

Nothing screams ‘spam-like adding “FW” or “RE” to the beginning of a subject line. Even using abbreviations or acronyms can be misconstrued. Having a good understanding of the intended message will allow you to avoid these traps. Additionally, make sure to double-check spelling errors and typos.

Adding one or two words can make a huge difference between emails that get read, and ones that end up in the spam bin. Experts suggest making full use of power words, including words like Urgent, Essential, Breaking, or Offers, or abbreviations and acronyms like BOGO (Buy One Get One).

Finally, never ever use all capital letters in emails. Not only does this often trigger spam filters, but it will also scare away readers – it looks like you’re yelling at them!


Although there may be some debate on the matter, the standard for email subject lines is increasingly leaning towards sentence case capitalization as a more polite and less formal way to send business correspondence. Learning to write effective emails takes time and practice, but understanding the importance of proper capitalization, using clear language, and paying attention to tone will help anyone get closer to mastering the art of crafting an email that stands out in the inbox.

Knowing when to use all caps, sentence cases, or title cases and how to craft compelling yet polite subject lines is useful information to have in any workplace. If unsure, it’s always best to err on the side of caution and shoot for sentence case capitalization– unless overwriting with enthusiasm is part of your company’s culture.

With these tips, you can ensure that your emails are delivered to intended recipients, not discarded in the junk folder!

If you want to learn How To Improve Email Marketing, feel free to check our other articles!

Frequently Asked Questions

Should subject be capitalized?

In general, simple school subjects should not be capitalized. However, titles of people, languages, and courses should be capitalized for clarity and accuracy.

Do you capitalize thank you in subject line?

Generally, you should not capitalize the phrase “thank you” when used in a subject line. It is considered incorrect grammar to do so and can undermine the impact of the sentiment.

However, it is ultimately up to your own stylistic preferences.

Do you capitalize all in an email greeting?

Yes, it is correct to capitalize all words in an email greeting. In salutations, the standard practice is to include the name of the recipient and to capitalize all nouns and the first letter of each word in the greeting. This ensures familiarity while also demonstrating proper etiquette.

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