Business letter etiquette is the set of unwritten rules that decide whether your correspondence reads as professional or amateur. The content might be perfect, but a first-name greeting to a senior client, a careless sign-off, or a wall of un-proofread text can quietly undermine you. Get the etiquette right and every letter reinforces your credibility. Here are the rules worth knowing, and the common mistakes worth avoiding.
The salutation is the first test. Use the recipient's courtesy title and surname — "Dear Mr. Reed," or "Dear Dr. Rivera," — unless you have a genuinely informal relationship. When you're unsure of someone's title or pronouns, "Dear [Full Name]," is a safe, respectful choice. Defaulting to first names or "Hey" in formal correspondence reads as presumptuous.
Professional doesn't mean stiff, but it does mean measured. Keep the tone courteous even when the subject is a complaint or a refusal — especially then. Avoid sarcasm, humor that could misfire, and anything that reads as passive-aggressive. When in doubt, err on the side of formality; it's easier to warm up a relationship than to recover from an overfamiliar opening.
Etiquette isn't only about politeness — it's about not wasting people's time. State your purpose in the first sentence, keep paragraphs short, and cut anything that doesn't serve the message. A concise letter respects the reader and gets a faster response.
Sloppy formatting signals carelessness. Use a standard block layout, one-inch margins, and a clean 11–12pt font, and make sure the salutation and sign-off agree — "Yours sincerely" with a named recipient, "Yours faithfully" without (UK); "Sincerely" or "Best regards" (US). For a full breakdown of the layout, see our guide to the business letter format.
Nothing erodes credibility faster than typos in a formal letter. Read it twice — once for meaning, once purely for errors — and, for anything high-stakes, have a colleague check it. Confirm the recipient's name and company are spelled correctly; getting those wrong is the one mistake readers rarely forgive.
Every letter you send is a small ambassador for you or your organization. Consistent etiquette builds trust, projects competence, and sets you apart from correspondents who don't bother. In client relationships especially, the care you show on the page is read as the care you'll show in the work. For the broader principles that apply to all correspondence — not just business — see our guide to letter writing etiquette.
Because your correspondence represents you before you're in the room. Proper etiquette signals professionalism, respect, and attention to detail — qualities readers assume will carry over into how you work.
Formal enough to show respect, but never robotic. Use courtesy titles, standard salutations and sign-offs, and a measured tone. When you're unsure, lean formal — it's the safer default with clients and senior contacts.
Being too casual too soon — a first-name greeting or an overfamiliar tone with someone you don't know well. Close behind is sending a letter with typos or a misspelled recipient name.
Many of the same principles carry across — a proper greeting, clear structure, courteous tone, and a fitting sign-off — though email is generally slightly less formal. A physical business letter still sets the higher bar.
Business letter etiquette isn't about rigid rules for their own sake — it's about respect made visible. Address people properly, keep the tone measured, format cleanly, and proofread every time. The Letter app helps with the presentation, applying a correct, professional layout so your etiquette shows on the page as clearly as in the words.
