Email deliverability best practices come down to five habits: authenticate every sending domain, mail only people who opted in, keep the list clean, send at a steady and predictable volume, and monitor results every week. None is a trick. Together they build a reputation that mailbox providers trust.
What should be in place before you send?
- SPF and DKIM published and passing, with a DMARC record at least at p=none. See the setup guide.
- A sending domain you own, ideally a subdomain such as mail.yourdomain.com for marketing, so it is separated from transactional and employee mail.
- A reverse DNS (PTR) record on your sending IP that resolves to a hostname, and TLS enabled for sending.
- A clear From name, a monitored reply address and a visible unsubscribe link.
How should you collect and treat subscribers?
Get clear permission and record where and when each address was collected. Confirmed opt-in is the strongest form, because it proves the owner of the mailbox said yes.
Set expectations at signup. If people sign up for a monthly newsletter and receive three emails a week, complaints follow. Remove hard bounces immediately and handle inactive contacts with a re-engagement series before suppressing them. The mechanics are in email list hygiene.
How should you send?
- Keep volume consistent. Sudden spikes look like compromised accounts. New domains need a warm-up.
- Segment by engagement and send to active contacts first.
- Keep subject lines honest and the HTML simple, with a plain-text alternative.
- Use one-click unsubscribe headers on marketing mail. See how to add them.
- Do not use link shorteners from public services in marketing mail.
What should you monitor?
Track complaint rate, bounce rate, unsubscribe rate and authentication results for every campaign. Gmail users can see spam rate and reputation in Postmaster Tools. Review blocklist status monthly, and run a placement test after any infrastructure change.
Google's sender guidelines ask bulk senders to stay below a 0.30% spam rate and recommend staying under 0.10%. Treat those as ceilings, not goals. See the full requirements.
How do these fit with a wider email program?
Deliverability is not separate from strategy. Welcome flows, order confirmations and post-purchase emails earn engagement that protects your reputation for the campaigns that follow. The big picture is in our email deliverability overview.
Frequently asked questions
What is the single most important deliverability practice?
Sending only to people who want your mail. Good permission and a clean list reduce complaints, bounces and spam traps, which are the biggest reputation damagers.
Do I need a separate domain for marketing email?
A dedicated subdomain is a good idea. It isolates marketing reputation from transactional and day-to-day business email.
How often should I clean my list?
Remove hard bounces after every send, and review inactive contacts on a schedule that suits your sending frequency, often quarterly.
Are images and HTML bad for deliverability?
Not by themselves. Very image-heavy emails with little text, broken HTML and missing plain-text parts do cause trouble.