The email campaign best practices that matter most in 2026 are the ones mailbox providers and the law enforce: send only to people who opted in, authenticate your domain, include one-click unsubscribe and a postal address, and keep complaints under 0.1%. After that, match the campaign to a single goal, personalize with real data, and judge it by replies and conversions rather than opens.
Pick one goal per campaign
Every campaign type has a different job, and a single email that tries to do all of them does none well.
| Campaign | Goal | Who gets it | What to measure |
|---|---|---|---|
| Newsletter | Keep subscribers informed and engaged | Opted-in subscribers | Clicks, replies, unsubscribes |
| Onboarding | Get a new user to their first success | New signups, triggered by their actions | Activation (did they do the thing?) |
| Product announcement | Get existing users to try something new | Active users | Clicks, feature adoption |
| Re-engagement | Find out who still wants your mail | Subscribers inactive for months | Who stays; remove the rest |
| Cold outreach | Start a conversation | A small, researched list of businesses | Replies, meetings |
Cold outreach carries the most risk. Keep lists small and relevant, write to one person at a time, and stop at the first reply or opt-out. Complaints from cold mail count against the same domain reputation as your product mail, so consider sending it from a separate domain.
Get consent and the legal basics right
In the US, CAN-SPAM applies to every commercial email, B2B included. The FTC's list:
- Accurate From, To, and routing information that identifies you.
- A subject line that reflects the content.
- A clear disclosure when the message is an ad.
- Your valid physical postal address.
- A clear way to opt out, honored within 10 business days.
- You stay responsible when someone else sends for you.
Gmail and Yahoo add their own rules for bulk senders: SPF, DKIM, and DMARC, one-click unsubscribe (RFC 8058) on marketing mail, and a spam complaint rate under 0.3% (Google, Yahoo). Yahoo asks you to honor unsubscribes within 2 days, faster than CAN-SPAM requires.
Mailmark adds the one-click unsubscribe headers and an unsubscribe footer to every campaign, with the business address you save on the domain. Authentication setup is in the DNS records guide.
Clean the list before you send
A campaign to a stale list is how good domains get bad reputations. Before every send:
- Remove hard bounces and past unsubscribes.
- Leave out people who haven't engaged in months, or send them a separate re-engagement message asking if they want to stay.
- Validate new or imported addresses. The free email list validator catches syntax errors, disposable domains, and domains with no MX record.
- Never buy or rent a list.
Write for one reader and one action
- One primary call to action. Decide the single thing you want the reader to do and make it obvious. Repeat it at the end of a long email if needed.
- A subject line that tells the truth. Specific beats clever, and CAN-SPAM requires it to match the content.
- Preview text that adds to the subject. Most clients show it after the subject line; don't let it default to "View in browser".
- A recognizable sender. Use a real name or your product's name, and an address on your own domain that accepts replies.
Personalize with real data
Personalization is more than a first name, but the first name has to work first. In Mailmark, merge fields use double braces with an optional fallback for missing values:
Hi {{FirstName|there}},
You signed up for {{Product}} on {{SignupDate}}. Here's the one setting
most teams change in their first week.
Use fields you actually have for every recipient, and set a fallback for the rest so nobody gets "Hi ,". Beyond merge fields, segment by behavior: what someone used, bought, or clicked last is a better reason to email them than a calendar date.
Follow up without annoying people
A short follow-up reaches people who missed or meant to answer the first message. The rule is to stop the moment someone responds. Mailmark's sequences stop automatically when a contact replies or a step bounces. Keep follow-ups short, add something new each time, and watch the complaint rate when you add steps.
Measure what tells you something
- Replies and clicks show real interest.
- Conversions (signups, activations, purchases) show whether the campaign did its job.
- Unsubscribes and complaints show whether people wanted it. A spike after one send is direct feedback on that send.
- Bounces show list quality.
Open counts are a weak signal on their own: treat them as a trend at most. Mailmark shows reach, opens, replies, and failed deliveries for each campaign, and bounce and complaint rates per domain on the domain health page.
Pre-send checklist
| Check | Done when |
|---|---|
| Sending domain authenticated | SPF, DKIM, and DMARC pass |
| List cleaned | No hard bounces, unsubscribes, or long-inactive recipients |
| Unsubscribe | One-click headers plus a visible link |
| Postal address | In the footer |
| Subject line | Matches the content |
| Merge fields | Every field has a value or a fallback |
| Single call to action | One obvious next step |
| Test send | Checked on desktop and phone, links clicked |
| Volume | Not far above your normal daily sending |
For the deliverability side in depth, see the email deliverability guide.
Frequently asked questions
How often should I send email campaigns?
As often as you said you would when people signed up, and consistently. A predictable schedule earns fewer complaints than irregular bursts, and sudden volume spikes hurt deliverability.
Does CAN-SPAM apply to B2B email?
Yes. The FTC says the law makes no exception for business-to-business email: every commercial message needs accurate headers, an honest subject line, a postal address, and a working opt-out.
Should I measure open rates?
Use them as a rough trend at most. Replies, clicks, conversions, unsubscribes, and spam complaints tell you more about whether a campaign worked.
How many follow-ups should a campaign have?
Enough to reach people who missed the first message, and no more. Stop as soon as someone replies or unsubscribes, and watch complaint rates when you add steps.