There is no single universal rule for email subject line capitalization — but there is a clear professional norm and a clear context where each style fits.

Sentence case ('Following up on our proposal') is the standard for professional business email. It reads as direct, conversational, and unforced. Most high-volume email senders (newsletters, SaaS companies, professional correspondents) use sentence case because it looks like something a real person wrote, not a marketing department.

Title case ('Following Up on Our Proposal') is common in marketing emails, press announcements, and formal correspondence. It signals that the subject has been crafted deliberately, like a headline. It works well for promotional emails, event invitations, and newsletters where you want the subject to feel like a published piece.

• ▸Professional email: sentence case — 'Quick question about Thursday's meeting'
• ▸Marketing email: title case — 'Your Exclusive Invitation to Our Webinar'
• ▸Newsletter: either works — pick one and use it consistently across all issues
• ▸Internal company email: sentence case almost always — 'Update on the Q3 roadmap'

The one rule that applies everywhere: do not capitalize random words in the middle of a subject line for emphasis. 'Following up on our Very Important Proposal' is not a capitalization style — it's an error.

The greeting line of an email (also called the salutation) has specific and consistent capitalization rules that most writers already follow instinctively — but get wrong in one specific way.

The correct rule: capitalize the first word of the greeting and any proper nouns (names, titles used as names). Do not capitalize the rest.

• ▸'Dear Sarah,' — correct. 'Dear' starts the greeting; 'Sarah' is a proper noun.
• ▸'Hi there,' — correct. Only 'Hi' is capitalized; 'there' is not a proper noun.
• ▸'Hello everyone,' — correct. 'Hello' starts the greeting; 'everyone' stays lowercase.
• ▸'Dear Hiring Manager,' — correct. 'Manager' is used as a title standing in for a name.
• ▸'Hi Team,' — correct in informal contexts. 'Team' here is used as a collective name.

The mistake most people make: capitalizing every word in the greeting. 'Dear Hiring Manager' is correct; 'Dear Hiring manager' is wrong; 'Dear hiring manager' is also wrong. The word directly after 'Dear' or 'Hi' only gets capitalized if it's a proper noun or a title used as a name.

One edge case: 'To Whom It May Concern' — this is treated as a title phrase and capitalized in title case by convention, even though the rules would suggest otherwise. It's an exception worth memorizing.

The body of a professional email should follow standard sentence case — capitalize the first word of each sentence and proper nouns only. This is identical to how you would write any professional document.

Common mistakes in email body text:

• ▸Capitalizing words for emphasis: 'This is Very Important' — lowercase 'very' and 'important'
• ▸Capitalizing job titles mid-sentence: 'I spoke with our Marketing Manager' — lowercase unless it directly precedes a name ('I spoke with Marketing Manager Sarah Chen')
• ▸Capitalizing product or department names inconsistently: decide once ('the sales team' or 'the Sales Team') and use it throughout
• ▸Capitalizing after a colon in the middle of a sentence: 'We have three options: First, second, or third' — lowercase after a mid-sentence colon

Email sign-offs (closings) follow a rule that many writers get exactly wrong: only the first word of the closing is capitalized, and the rest are lowercase.

• ▸'Best regards,' — correct. Not 'Best Regards,'
• ▸'Kind regards,' — correct. Not 'Kind Regards,'
• ▸'Many thanks,' — correct. Not 'Many Thanks,'
• ▸'Yours sincerely,' — correct. Not 'Yours Sincerely,'
• ▸'Thanks,' — correct (single word, no issue)
• ▸'Best,' — correct (single word, no issue)

The reason: closings are treated grammatically like the end of a sentence — only the first word is capitalized. 'Best Regards' reads as two proper nouns, which they are not. This is one of the most widespread capitalization errors in professional email.

The exception is any proper noun that appears in the closing. 'See you in New York,' — 'New York' is always capitalized regardless of position.

When you include a list in an email, capitalization follows a simple rule: capitalize the first word of each bullet point, regardless of whether each point is a complete sentence.

If the list is introduced by a complete sentence ending in a colon, each bullet point starts with a capital letter.

If the list is a continuation of an incomplete introductory sentence (the sentence 'flows into' the first bullet), the convention is less strict — some writers capitalize, some don't. The safest approach is to always capitalize the first word of each bullet for visual consistency.

The one thing to avoid: capitalizing only some bullet points and not others. Inconsistency within a list signals carelessness more than any individual capitalization choice does.