Email Marketing Best Practices: Deliverability, Metrics, Platforms and Law

Start with the failure you see, and fix the earliest failing step first. Copy and design cannot help mail that never reaches the inbox.

Use the strictest rule that applies to your volume as your working standard. The three providers set different limits, so meet each one, not only the easiest.

Google says a sender that meets its criteria once stays a bulk sender permanently. Plan authentication for that status, not for the volume you send this month.

Google says it is ramping up enforcement on non-compliant traffic, with temporary and permanent rejections. Fix the gaps before you add volume.

Google also asks for valid reverse DNS records on each sending IP address, pointing to your domain, and for a TLS connection when you transmit mail. Check both on every sending server.

Google's one-click rule covers marketing and subscribed mail only. Apply it to those streams.

Validity lists an engagement-sorted Most Relevant view of the Promotions tab in Gmail, and expects senders with lower engagement to become less visible in Gmail inboxes.

For the DNS records and the warm-up steps, read the deliverability guide.

Stop using opens as your main success measure. Apple's privacy feature downloads mail content in the background, so an open can register whether or not anyone reads the message.

Apple sends that content through two separate relays run by different entities, so no single party can link an IP address to the content.

Litmus's market share report, built on over 1.5 billion opens, puts Apple at 76.56% and Gmail at 16.10%. Apple and Gmail together make up nearly 90% of the total.

Litmus cites studies putting Apple's feature at roughly 55 to 60% of all email opens. Open rates therefore overstate engagement on any list with many Apple Mail readers.

Compare open rates only within the same mix of mail clients. Read clicks and revenue as the main signals, and track these instead:

• Click rate per send, by segment and by flow.
• Orders or sign-ups from each email, in an attribution window you set before the send.
• Revenue per recipient, reported for flows and campaigns separately.
• Unsubscribe and spam complaint rates, which providers set limits on.

Litmus's 2025 State of Email survey reports the spread of ROI, not an average. 35% of marketers report $10 to $36 returned per $1 spent, 30% report $36 to $50, and 5% report more than $50.

Litmus also reports that 21% of marketing leaders do not measure ROI, down from 36% in 2023.

Set your own lift with a holdout group, then compare it with the range above. The email marketing overview covers how to design the holdout and which benchmarks to test against.

Build the flows before you fill the campaign calendar. Each flow needs a trigger, an exit rule and a holdout group before launch.

In Klaviyo's benchmark data, campaigns make up 94.7% of send volume. Flows generate nearly 41% of email revenue from 5.3% of sends.

The same data puts revenue per recipient for flows nearly 18 times higher than for campaigns.

The data comes from the vendor's own customers and skews toward ecommerce. Treat it as a benchmark, and check whether it holds for your list.

Set a holdout group for each flow. A group that receives no flow emails shows the revenue the flow adds, which open and click figures cannot show.

For the flow set, triggers and segmentation rules, read the automation guide. For subject lines and calls to action in each flow, read the copywriting guide.

Price each platform at the contact count and send volume you expect in the next year, not at today's size. Platforms charge on different units, so compare the same volume on each.

Some platforms charge by contact count and others by send volume, so one list size can cost very different amounts. The email service providers guide sorts the platforms into SMB, mid-market and enterprise tiers by contact count.

Mailchimp's pricing page lists a free plan with a limit of 250 contacts.

Use a free plan to test the setup, not to run a list that keeps growing. Test placement on your own list before you migrate, and do not treat a comparison post's placement rate as a result.

Map each list segment to the rules that cover its recipients before you send to it. Then confirm each rule in the email compliance guide.

The CAN-SPAM Rule decides whether an email is commercial by its primary purpose, and its criteria make no exception for business recipients. A B2B list needs the same opt-out process as a consumer list.

CAN-SPAM also covers materially false header information, deceptive subject headings, clear identification of the message as an advertisement, and anyone acting on your behalf after an opt-out request. Monitor agencies and vendors who send for you.

Every commercial email must show a valid physical postal address of the sender, and an opt-out request must be honored within 10 business days. Check that your ESP footer carries the address on every template, including automated flows.

The GDPR sets a higher and a lower tier of fines. The higher tier covers breaches of the basic principles, including the conditions for consent.

Keep a consent record for each contact, because the higher tier names the consent conditions directly.

The compliance guide covers Canada's CASL, the CCPA and CPRA thresholds and penalties for California, and a global checklist.