Email campaigns work by sending targeted messages to a list of subscribers through an email service provider (ESP), which handles the technical delivery, tracks engagement, and lets you automate sends based on timing or subscriber behavior. The process has several moving parts, from building your list and writing the emails to getting them past spam filters and measuring whether people actually opened and clicked. Here’s how each piece fits together.
Building a Subscriber List
Every email campaign starts with a list of people who have agreed to receive your messages. You collect email addresses through signup forms on your website, checkout pages, social media links, or in-person events. How you confirm those signups matters more than most beginners realize.
With single opt-in, someone fills out a form and they’re immediately added to your list. It’s fast and frictionless, but it also means typos, fake addresses, and people who didn’t fully intend to subscribe can end up on your list. Double opt-in adds one extra step: after submitting the form, the person receives a verification email and must click a confirmation link before they’re added. That extra click filters out bad addresses and disinterested signups, which leads to fewer spam complaints and better deliverability over time. If your emails consistently bounce or get marked as spam, inbox providers start treating all your messages with suspicion, so list quality directly affects whether your campaigns reach anyone at all.
How Emails Get Delivered
When you hit “send” on a campaign, your email service provider doesn’t just fire off thousands of messages at once to a brand new account. The ESP routes your emails through its servers, which have assigned IP addresses. Internet service providers (ISPs) like Gmail and Outlook evaluate those IP addresses the same way a bank evaluates a credit score: senders with a good track record land in the inbox, while unfamiliar or flagged senders get filtered to spam or blocked entirely.
This is why new senders go through a process called IP warming. Instead of blasting your full list on day one, you send emails in small batches and gradually increase volume over days or weeks. This gives ISPs time to observe your sending patterns and confirm you’re following best practices. If your early batches generate low complaint rates and decent engagement, your IP builds a positive reputation, and future sends are more likely to reach the inbox. Skip this step, and a large ISP may flag your IP as suspicious before your campaign even gets going.
Two Types of Campaigns
Most email marketing falls into two categories, and understanding the difference helps you decide which to use and when.
Broadcast Emails
A broadcast is a one-time email sent to your entire list, or a segment of it, at a scheduled time. You write the message, choose who receives it, pick a send date, and the ESP delivers it. Every recipient gets essentially the same content, aside from basic personalization like inserting their first name. Broadcasts work well for newsletters, seasonal promotions, company announcements, or any message tied to a specific moment. Once it’s sent, it’s done.
Automated Sequences
An automated sequence (sometimes called a drip campaign or funnel) is a series of emails that sends itself based on triggers. You set it up once, and it runs in the background indefinitely. The trigger might be someone signing up for your newsletter, abandoning a shopping cart, making a purchase, or clicking a specific link. Each action can kick off a tailored series of follow-up messages spaced out over days or weeks.
For example, when a new subscriber joins your list, they might automatically receive a welcome email on day one, a second email introducing your best content on day three, and a promotional offer on day seven. Someone who buys a product might get an order confirmation, a shipping update, and then a follow-up email two weeks later suggesting a related item. Because these emails respond to individual behavior, they tend to feel more relevant and generate higher engagement than broadcasts sent to everyone at once.
What the Law Requires
In the United States, commercial email is governed by the CAN-SPAM Act, enforced by the Federal Trade Commission. The rules apply to any message whose primary purpose is advertising or promoting a product or service, and violating them can result in penalties per individual email sent. The core requirements are straightforward:
- Accurate sender information. Your “From” name, email address, and reply-to address must honestly identify who sent the message. You can’t disguise your identity or use misleading routing information.
- Ad disclosure. If the email is an advertisement, you need to say so. The law gives flexibility in how you disclose this, but the disclosure must be clear.
- Physical address. Every marketing email must include your valid postal address. This can be a street address, a registered P.O. box, or a private mailbox registered through a commercial mail receiving agency.
- Unsubscribe mechanism. You must give recipients a clear, easy way to opt out of future emails. This typically means an unsubscribe link at the bottom of the message. The mechanism must remain functional for at least 30 days after the email is sent.
- Prompt opt-out processing. Once someone unsubscribes, you have 10 business days to stop sending them marketing emails. You can’t charge a fee, require personal information beyond an email address, or make the person jump through multiple steps to opt out.
Most ESPs handle much of this automatically. They’ll insert an unsubscribe link, process removal requests, and require you to include a physical address in your account settings. But the legal responsibility is yours, not the platform’s.
Measuring Whether Campaigns Work
After a campaign sends, your ESP generates a report with several key metrics. Knowing what each one means, and what counts as a reasonable benchmark, keeps you from guessing.
Open rate tracks what percentage of recipients opened your email. It used to be the go-to metric, but Apple’s Mail Privacy Protection feature now pre-loads tracking pixels for many users, which inflates open counts. Open rate still gives a rough signal, but it’s no longer precise enough to rely on as your primary measure.
Click-through rate (CTR) is the more reliable indicator. It measures the percentage of delivered emails that generated at least one click. For general marketing emails like newsletters and announcements, a CTR between 2% and 5% is considered solid. Promotional emails tend to land a bit lower, in the 1% to 3% range. Transactional emails, like order confirmations and shipping notifications, often exceed 5% because recipients are actively expecting them.
Click-to-open rate (CTOR) goes a step deeper. Instead of measuring clicks against all delivered emails, it measures clicks only among people who opened the message. This tells you how compelling your content was to the people who actually saw it. A CTOR above 20% is generally strong. Content-rich or educational emails can hit 20% to 30%, while promotional messages typically fall between 5% and 15%.
Beyond clicks, you’ll also track bounce rate (emails that couldn’t be delivered), unsubscribe rate, and conversion rate (how many recipients completed a desired action like making a purchase or filling out a form). A rising bounce rate signals list quality problems. A climbing unsubscribe rate may mean you’re sending too frequently or your content isn’t matching what subscribers expected when they signed up.
Putting It All Together
The typical workflow looks like this: you build a list using opt-in forms, segment that list based on characteristics or behavior (new subscribers, past buyers, people in a certain location), create your email content, and send it through your ESP either as a one-time broadcast or an automated sequence tied to triggers. The ESP handles routing the message through properly warmed IP addresses, manages unsubscribe requests, and collects performance data so you can see what’s working.
Each campaign you send feeds the next one. If a particular subject line drove a higher click-through rate, you can test a similar approach next time. If a segment of your list consistently ignores your emails, you can try re-engagement campaigns or remove inactive subscribers to keep your sender reputation healthy. The whole system is a loop: send, measure, adjust, and send again.