20 Formal vs Informal Email Phrases (Side-by-Side)
20 formal and informal email phrases compared side by side — so you can choose the right register for your audience every time.
Choosing between formal and informal email phrases is about matching your register to your reader, not following a single rule. Write formally to new contacts, senior stakeholders, and external clients you don’t know well. Write informally to close colleagues and managers you talk to daily. Below are 20 phrases compared side by side, covering openings, requests, apologies, closings, and common transitions.
Why Register Matters More Than Grammar
A grammatically perfect email in the wrong register sounds wrong. “I trust this communication finds you in good health” to your team Slack is bizarre. “Hey, what’s up with the report?” to the CFO is inappropriate. The mistake most non-native speakers make isn’t grammar — it’s mismatching the formality level to the relationship.
English has a broad formality range. The same meaning can be expressed at completely different registers, and choosing the right one signals that you understand your relationship with the reader.
Opening Lines
| Informal | Formal |
|---|---|
| ”Hi [Name]," | "Dear [Mr./Ms. Last Name]," |
| "Hey [Name]," | "Dear [Title] [Last Name]," |
| "Hope you’re having a good week" | "I hope this email finds you well" |
| "Just a quick note to…" | "I am writing to…" |
| "Wanted to let you know…" | "I wish to inform you that…” |
Which to use when: Use formal openings for first contact with an external client, a job application, a formal complaint, or any communication with an executive you haven’t met. Use informal openings with colleagues you interact with regularly — “Hi” is appropriate for most internal emails.
A middle ground that works well for most professional situations: “Hi [Name],” as the greeting, and get directly to your point without an opener like “Hope you’re well.” This is professional without being stiff.
Making Requests
| Informal | Formal |
|---|---|
| ”Can you send me…?" | "Could you please forward…?" |
| "Send this by Friday" | "I would appreciate receiving this by Friday" |
| "Let me know what you think" | "I would welcome your feedback" |
| "Can you look into this?" | "I would be grateful if you could investigate this matter" |
| "I need this done by Monday" | "I would kindly request that this be completed by Monday” |
Note on “Could you please”: “Could you please” sits in a comfortable middle zone — it’s polite but not overly formal. It works in most professional contexts, from internal requests to external client communication. It’s the phrase to use when you’re unsure which register to choose.
Declining or Pushing Back
| Informal | Formal |
|---|---|
| ”I can’t make that work this week" | "Unfortunately, I’m unable to accommodate this within the requested timeframe" |
| "That doesn’t work for me" | "I’m afraid this falls outside what I’m able to commit to at this time" |
| "I disagree with this approach" | "I have some reservations about this approach that I’d like to discuss" |
| "Can we push this to next week?" | "Would it be possible to extend the deadline to [specific date]?” |
The British “I’m afraid”: “I’m afraid I can’t attend” is standard British English for “Unfortunately I can’t attend.” It does not express actual fear. Non-native speakers sometimes avoid it because it sounds emotional, but in British and Irish professional contexts it’s entirely standard and appropriate.
Apologies and Acknowledgments
| Informal | Formal |
|---|---|
| ”Sorry for the late reply" | "Please accept my apologies for the delayed response" |
| "My mistake" | "I apologize for the error" |
| "Got it, thanks" | "Duly noted, thank you" |
| "Thanks for your patience" | "I appreciate your understanding in this matter" |
| "Oops, forgot to attach this" | "Please find the attachment, which I inadvertently omitted from my previous message” |
On “Sorry for the late reply”: This is acceptable in most professional contexts but often unnecessary. If you’re replying a day late to a non-urgent email, you don’t need to apologize. “Thanks for your patience” is warmer than “sorry for the late reply” because it thanks the reader rather than drawing attention to your own delay.
Closing Lines
| Informal | Formal |
|---|---|
| ”Let me know if you have questions" | "Please do not hesitate to contact me should you require further information" |
| "Talk soon" | "I look forward to hearing from you" |
| "Thanks!" | "Thank you for your time and consideration" |
| "Best," | "Yours sincerely,” or “Kind regards," |
| "Cheers," | "With best regards,” |
On “Yours sincerely” vs “Yours faithfully”: In British English: use “Yours sincerely” when you’ve used the person’s name (Dear Sarah). Use “Yours faithfully” when you’ve used “Dear Sir/Madam.” This distinction is rarely taught in language classes but is noticed by British readers.
In American English: “Sincerely” is the most formal sign-off. “Best regards” and “Kind regards” are professional but slightly warmer. “Best” is standard for ongoing correspondence.
How to Calibrate When You’re Not Sure
When you don’t know your reader’s preferred register, start one level more formal than you think is necessary. It’s easier to relax into informality over time than to repair the impression made by being too casual too early.
After two or three exchanges, mirror the formality level of the person you’re writing to. If they open with “Hi” and sign off with “Thanks,” match that. If they use “Dear” and “Kind regards,” maintain that register.
For a complete collection of phrases organized by scenario, see our business English phrases guide and the guide to email sign-offs.
FAQ
Is it wrong to use informal English in a professional email?
Not if you’re using it with the right person at the right time. Informal English in a team Slack message or a quick email to a colleague you see daily is perfectly appropriate. Informal English to a new client or senior executive you’ve never met is a misstep.
What’s the most common formality mistake non-native speakers make?
Overuse of very formal language in everyday contexts. Phrases like “I wish to inform you” and “I trust this message finds you well” sound stilted in modern business English unless you’re writing a formal letter or the first contact with a very senior person. Most workplace emails call for a professional-but-direct register, not a formal-document register.
How do I know if my email is too formal?
Read it aloud. If it sounds like a Victorian legal document, it’s too formal. If a native speaker in your office would raise an eyebrow at the language, it’s too formal. “Hi [Name], I’m following up on our conversation about the Q2 timeline — let me know if you need anything from me” is the right register for 80% of professional email.
Are formal phrases ever required in American business English?
Rarely. American business writing tends to value directness and informality over formal register. You’ll use formal language in official HR communications, legal correspondence, and some executive communications — but most American workplace email sits firmly in the informal-to-moderate range.
Can I mix formal and informal phrases in the same email?
You can, but be careful. Opening with “Dear Ms. Johnson” and ending with “Cheers!” creates register dissonance that feels slightly off. Consistent register throughout the email is more professional. If you’re not sure, use the moderate middle ground throughout.