Should email subject lines be capitalized?
There is no grammar rule that forces either style. But your choice changes how an email feels, and one style is a clear mistake.
No rule says email subject lines must be in Title Case. Sentence case ("Your order has shipped") feels personal and is the safer choice for work, sales and newsletter emails. Title Case ("Your Order Has Shipped") feels more formal or like a headline. Pick one and use it consistently. Avoid ALL CAPS: it reads as shouting and can look spammy.
The three styles
| Style | Example | Feels |
|---|---|---|
| Sentence case | Quick question about Friday's meeting | Personal, conversational |
| Title Case | Quick Question About Friday's Meeting | Formal, like a headline |
| ALL CAPS | QUICK QUESTION ABOUT FRIDAY'S MEETING | Shouting, spammy |
When to use sentence case
- Emails to colleagues, clients and people you know.
- Sales and cold emails, where you want to sound like a person, not a campaign.
- Newsletters with a friendly voice.
- Replies and follow-ups.
Sentence case also looks like the emails people get from friends, which is one reason many marketers prefer it.
When Title Case fits
- Formal announcements, press releases and official notices.
- Event names, report titles and product names.
- Organizations whose style guide uses Title Case everywhere.
Even in sentence case, keep capitals on names, brands and proper nouns: "Your Netflix plan changes in May".
Why to avoid ALL CAPS
Capital letters across a whole subject line read as shouting, are harder to read, and are a classic pattern of spam. One capitalized word for emphasis, such as "FREE" or "LAST", is less risky, but there is usually a better way. See subject lines and spam words to avoid.
If you use Title Case: the rules
- Capitalize the first and last word, and all nouns, verbs, adjectives and adverbs.
- Keep short words lowercase in the middle: a, an, the, and, but, or, for, of, on, in, to, at, by.
- Capitalize both parts of hyphenated words in most styles: "Year-End Sale".
The real rule: be consistent
Readers notice when a sender switches back and forth. Choose a style for each type of email and stick to it. Before you send, preview the subject with the free subject line tester to see how it looks in the inbox, and pair it with good preheader text.
Questions people ask
- Is it correct to capitalize every word in an email subject line?
- It is not wrong. That is Title Case, and it fits formal emails. For most everyday and marketing emails, sentence case reads more naturally.
- Does capitalization in subject lines affect open rates?
- It changes the tone, which can matter, but results differ by audience. Test both styles on your own list if it is important to you.
- Is ALL CAPS in a subject line bad?
- Yes. It reads as shouting, is harder to read and resembles spam.
- Does capitalization matter in an email address?
- No, almost never. See are email addresses case sensitive for the details.