Email Etiquette, How To Sign Off An Email Professionally

TL;DR: 

• In the age of AI-generated correspondence, professional email sign-offs are small, but vital, markers of "humanity" and brand congruence.
• The choice of closing (e.g., Best, Warm, Kind Regards) should match the existing relationship and your brand's tone; a mismatch can feel awkward or unprofessional.
• The new rule for professional email is congruence—focus on speed-to-lead and resolution over excessive "warmth," as customers prioritize helpfulness from both human and AI agents.

We’ve all accidentally signed a work email off with ‘love’ or maybe even added a kiss or two without thinking but in the world of business, the humble email sign-off has become a bit of a battlefield. Starting with the stiff "Sincerely" to the ubiquitous "Best Regards," and now the rise of the slightly fuzzier "Warm Regards." For mid-market leaders managing teams and thousands of leads, it raises a fair question: 

Does the choice of a closing word actually impact your bottom line, or is it just digital noise?

As it turns out, in an era where AI generates half of our correspondence, these small markers of "humanity" matter more than ever. But there’s a fine line between being personable and being unprofessional - we’re looking at you ‘stay golden’! 

The "Regards" Spectrum

If you’re running any business, your email tone needs to match your brand's "boots-on-the-ground" reliability. Choosing the wrong sign-off can make you sound like a cold machine or, conversely, like you’re trying way too hard to be friends with someone you’ve never met.

So what connotations do the most commonly used email sign offs generate? 

• Best Regards: The "Old Reliable." It’s the safe, neutral choice for first-time outreach or formal business. 2025 research suggests it remains the most popular sign-off because it balances respect with professionalism according to Grammarly. 
• Warm Regards: This is for the "inner circle." It implies an existing relationship. If you use this on a cold lead, it can feel a bit like a stranger giving you a hug in a grocery store—unexpected and slightly uncomfortable.
• Kind Regards: The perfect middle ground. It adds a touch of empathy without the "intimacy" of warmth. It’s particularly effective when delivering news that isn't a "yes," like a politely declined bid.
• Best: The "Busy Executive" version. It’s punchy and modern, but be careful—some more traditional stakeholders still view it as a bit abrupt or lazy.

AI and the "Authenticity Gap"

Did you know…

72% of people are happy for AI to handle their customer service, but only 13% believe generative AI is actually better at writing the content than a human.

Source

People can smell "formulaic" a mile away. If your AI Sales Agent sends a perfectly polished email but signs it "Warmest Heartfelt Regards" to someone who just asked about a price for 500 bricks, the "uncanny valley" alarm goes off. The goal of an AI agent isn't to trick the customer into thinking it's a human; it's to provide human-level helpfulness with machine-level speed.

• Transparency Wins: Customers report 34% higher satisfaction when they know they're talking to an AI, provided it actually solves their problem (COPC, 2025).
• Focus on Resolution, Not Fluff: A lead would much rather have a "Best Regards" from an agent that just booked their appointment than a "Warmest Wishes" from one that keeps looping.

The New Rules of the Inbox

So, do people still care? Yes, but not in the way they used to. They care about congruence. If your email is short, punchy, and functional (the SalesApe way), your sign-off should be too.

Don't overthink the "warmth." Focus on the "speed-to-lead." An AI Sales Agent that responds in under five minutes with a simple "Thanks," and then accurately routes that lead to your human team, is doing more for your brand than a human Sales Development Rep who takes four hours to craft a "sincere" response that the lead has already ignored.

Frequently Asked Questions (FAQs)

Q. Does the choice of an email sign-off actually impact our business or bottom line?

Yes, in the age of AI-generated correspondence, the small marker of a professional email sign-off is a vital signal of "humanity" and brand congruence. A mismatch between the closing and the relationship/brand tone can feel awkward or unprofessional.

Q.  What are the connotations of the most common sign-offs?

• Best Regards: The "Old Reliable"—safe, neutral, and the most popular choice for formal business or first-time outreach.
• Warm Regards: Imply an existing, "inner circle" relationship. Using it on a cold lead can feel unexpected and slightly uncomfortable.
• Kind Regards: The perfect middle ground, adding empathy without intimacy. Effective for delivering news that is not a "yes."
• Best: The "Busy Executive" version—punchy and modern, but can be viewed by traditional stakeholders as lazy or abrupt.
• Catch you on the flip side: No! Just no! 

Q. In an era of AI correspondence, what is the "New Rule of the Inbox" for sign-offs?

The new rule is congruence. Instead of overthinking "warmth," the focus should be on "speed-to-lead" and resolution. Customers prioritize helpfulness from both human and AI agents, so the sign-off should match the email's tone: if the email is short and functional, the sign-off should be too (e.g., a simple "Thanks," or "Best").

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