The 30/30/50 rule for cold emails, explained

You may have seen the 30/30/50 rule for cold emails mentioned in a thread or a course, usually in one sentence with no explanation. It sounds precise, but the versions disagree with each other, and the numbers add up to 110.

This guide covers what people usually mean by it and which part is useful. It then turns the rule into a checklist you can run every email through.

What people mean by the 30/30/50 rule

The rule has no single source, so you will see a few readings. These are the common ones:

• An effort split. Spend about 30% of your writing effort on the subject line and 30% on the opening line. Put 50% into the rest of the email: the offer, the proof and the ask.
• An attention split. The subject line decides whether the email gets opened. The first line decides whether it gets read, and the body decides whether it gets a reply. The numbers describe how much each part matters, not how long it is.
• A content split. Some people use the numbers to describe what the email covers. One share goes to the reader's situation and one to the problem. The biggest share goes to what you offer and what happens next.

All three readings make the same point. The subject and the first sentence are the shortest parts of the email, but they deserve more care than their word count suggests. A reader who drops out at either one never sees your offer.

This article uses the first reading because it is the easiest to act on. It also matches the order a reader experiences your email: subject and preview, then opening line, then everything else.

Why the numbers don't add up, and why that doesn't matter much

30 + 30 + 50 is 110. That would be a problem if the rule came from measurement, but it doesn't. We could not find any research behind it. It is a rule of thumb that spread because it is easy to remember.

That is fine if you treat it as a priority order rather than a formula. Read plainly, it says:

1. Don't write the body first and add a subject line at the end.
2. Don't open with your name, your company or a pleasantry.
3. Use the remaining space for one offer, one piece of proof and one easy question.

You can read the extra 10% as a reminder that doing this properly takes longer than you planned. Nobody is grading the arithmetic. What matters is whether each part does its job before the reader decides to stop.

The first 30: the subject line and preview text

In most inboxes, the reader sees three things before opening: your name, the subject line, and a preview of the first line of the body. Treat them as one unit. A sharp subject followed by a preview that says "Hope this email finds you well" wastes the work.

Cold email subject lines tend to work when they are:

• Short and plain. A few words that would look normal coming from a colleague. Lowercase is fine.
• Specific to the reader. Use the business name, the town, the service, or the thing you noticed.
• Accurate. The subject must describe what is inside. Fake "Re:" or "Fwd:" prefixes break trust, and deceptive subject lines run against CAN-SPAM in the US.
• Free of hype. Exclamation marks, all caps, and words like "free" or "guaranteed" make the email read like an ad rather than a note.

Examples for a local business:

• booking link on Maple Dental's listing
• question about your emergency page
• Ridgeline + after-hours calls

Next, check the preview. The reader will see the start of your first sentence next to the subject. If the subject raises a question and the preview starts to answer it, you have done this part well. For more options, see these cold email subject lines that get opened.

The second 30: the opening line that earns the read

The opening line has one job: show that this email was written for this reader. The quickest way is to lead with something you checked about them, not with who you are.

Weak openers are either about the sender or could be sent to anyone:

• "My name is Sam and I run a marketing agency."
• "I hope you're having a great week."
• "I came across your business and was impressed."

Strong openers name something specific that the reader can check:

• "Your Google listing says you do same-day repairs, but the website only lists weekday hours."
• "I saw you added Saturday classes last month."
• "Three of your recent reviews mention waiting on hold to book."

Two rules keep the opener honest:

1. State what you observed, not what you assume it means. "I couldn't find a booking link on your homepage" is fair. "You're losing customers because you have no booking link" is a claim you can't back up.
2. Leave room to be wrong. Asking "Is there a page I missed?" invites a reply even if your observation is off.

Researching openers one at a time is the slow part. Prospect Cheap reads each lead's website and writes a short summary with first-line ideas you can edit, so you start from a draft instead of a blank page. Check every detail before it goes out. For doing this across a whole list, see how to personalize cold email at scale.

The 50: the offer, the proof and the ask

Once someone is reading, the rest of the email has to answer three questions quickly:

1. What do you do for businesses like mine?
2. Why should I believe you?
3. What do you want from me?

The offer

Use one sentence and one outcome, not a list of services. "I build simple booking pages for physical therapy clinics" is clearer than "We offer web design, SEO, PPC and social media." If you can't say what you offer in one line, fix the offer before you work on the email. How to write a cold email offer people want walks through the process.

The proof

Use one short, true line. That could be a client in the same trade, a result you can stand behind, or a sample you can send.

If you don't have proof yet, either leave it out or offer a small free deliverable that works as proof. A screenshot, a short screen recording or a one-page outline all do this. Never invent a client or a number.

The ask

Make the ask small and answerable with yes or no. Agreeing to receive something is easier than committing to a 30-minute call through a calendar link. Good asks look like this:

• "Want me to send the screenshot?"
• "Worth a look?"
• "Should I send a short outline of how it would work?"

For more examples, see cold email calls to action that get replies.

Body length

The rule puts half your effort into this part, not half your words. A first email should be a few short paragraphs that fit on a phone screen without scrolling.

Under about 100 words is a sensible drafting limit. Treat it as a constraint that helps you cut, not as a proven threshold. Your sender details and opt-out line are extra.

Applying the rule to emails for local business owners

Local owners read email differently from corporate buyers. They often check it on a phone, between jobs, from a shared inbox. Here is how that changes each part of the rule:

• Subject: Use the business name or the town. Owners recognize their own business name right away.
• Opening: Point to something public they will recognize, such as their Google listing, their Yelp page, a recent review, or their website on mobile. Use their words: "customers," "the shop," "jobs," not "conversion funnel."
• Offer: Tie it to something they deal with every day, like missed calls, no-shows or slow weeks, rather than a marketing metric.
• Ask: Keep it to something they can answer in one tap. Leave links and attachments out of the first email and offer to send them instead.

You also need to reach the right person. At a small business the owner usually decides, and writing to them by name beats "Hi there."

If you pull leads from Google Maps or Yelp with Prospect Cheap, its AI looks on each business's website for the owner's name and title, emails and social profiles. That means the "Hi Dana" in your template comes from a real source. When no owner name turns up, a short, polite note to the main inbox of a single-location business often still reaches someone who can decide.

For tested starting points, see these cold email templates for local businesses.

A before-and-after rewrite of a local business cold email

Below is the kind of email many local owners get every week. The business and sender are fictional, but the pattern is very common.

Before

Subject: Grow Your Business With Our Proven Marketing Solutions!!

Hi there,

My name is Jake and I'm the founder of BrightPath Digital, a full-service agency with over 10 years of experience helping businesses of all sizes reach their goals. We offer SEO, PPC, social media management, web design and much more.

I came across your business online and see a lot of potential for growth. Our team of experts would love to help take your online presence to the next level.

Do you have 30 minutes this week for a call? Here's my calendar: [link]

Looking forward to hearing from you!

Here is how it scores against the rule:

• Subject and preview: Generic, shouty, and could go to any business. The preview reads "My name is Jake and I'm the founder of...", which gives the reader nothing.
• Opening line: All about the sender. "I came across your business" is the only nod to the reader, and it says nothing specific.
• The 50: Six services and no outcome. The only proof is a claim about years in business, and the ask is a large one with a link attached.

After

Subject: emergency page, Ridgeline

Hi Dana,

Your Google listing says Ridgeline Plumbing takes 24/7 emergency calls, but on my phone the "Call now" button on your site opened a blank page (checked Tuesday, iPhone, Safari).

I build simple service pages for plumbers around Fort Collins so urgent callers can reach you in one tap.

Want me to send a 30-second screen recording of what I saw?

Jake, BrightPath Digital, [postal address]

Not useful? Reply "no" and I won't follow up.

What changed:

1. Subject: It names the business and the topic in three words. The preview now opens with "Your Google listing says...", which is about Dana, not Jake.
2. Opening: It makes one specific observation and says when and how it was checked. Dana can confirm it in ten seconds.
3. Offer: One service and one outcome, tied to a trade and a town.
4. Proof: The screen recording works as the proof. If Jake has a real plumbing client, one line about them could go before the ask. If he doesn't, he leaves it out.
5. Ask: A yes-or-no question with no link and no meeting request.
6. Footer: The sender's identity, postal address and a way to opt out all stay in.

The new body is around 75 words, compared with about 100 in the original. The word count isn't the main improvement, though. Every sentence now does one of the three jobs.

Where the rule falls short: lists, deliverability and follow-ups

The rule only covers writing. Plenty of cold campaigns fail for reasons a rewrite won't fix.

The list. A perfect email sent to the wrong business gets no reply. Stick to one category and one area per campaign, and check that each lead fits. Get a real person's name wherever you can. Live sources help here. Prospect Cheap collects businesses from Google Maps, Yelp, Trustpilot and other sites, so your list shows who is open and listed today rather than relying on an old database.

Deliverability. If the email lands in spam, nobody sees the subject line. Set up SPF, DKIM and DMARC, and send from a separate domain you have warmed up. Verify addresses before sending to keep bounces low, and keep the first email plain text. The basics are in cold email deliverability.

Follow-ups. Many replies arrive after the first email, but the rule says nothing about sequences. Write two or three short follow-ups that each add one new detail. Stop as soon as someone replies or opts out. Once your list is ready, you can send it from Prospect Cheap straight into an Instantly, Smartlead or lemlist campaign, or into GoHighLevel, and run the sequence there.

Testing. The rule tells you where to look when results are poor, but only your own numbers tell you what works. Change one part at a time (the subject, the opener or the ask) and compare replies, not opens.

A quick checklist to review each email against the rule

Run every draft through this list before it goes into a sequence.

Subject and preview (the first 30)

• Reads like a short note from a person, not an ad
• Mentions the business, the town, the service or the thing you noticed
• Accurately describes what's inside, with no fake "Re:"
• The first line of the body works as a preview

Opening line (the second 30)

• Starts with the reader, not with you
• Names one specific detail the reader can check
• States an observation, not a claim you can't support
• Would make no sense if sent to a different business

Offer, proof and ask (the 50)

• One offer in one sentence, tied to an outcome the reader cares about
• Proof is true, brief and relevant, or left out
• One ask that can be answered with yes or no
• No links, images or attachments in the first email
• Fits on a phone screen without scrolling

Everything around it

• Sender name, business and postal address included
• A clear way to opt out
• Recipient's email address verified
• Follow-ups written and stop rules set

Next steps

1. Take your most recent cold email and score each part against the checklist.
2. Rewrite the subject and first line first. Then cut the body down to one offer, one proof and one ask.
3. Send the new version to a small batch in one niche and one area, and compare replies with the old version.
4. If replies stay low once the writing passes the checklist, check your list and deliverability before rewriting again.