Email Deliverability Checklist: 10 Rules So Your Emails Reach the Inbox

The email you spent an afternoon writing can be technically "sent" and still never be seen, because it landed in spam or in a promotions tab nobody opens. Spam filters, crowded inboxes and privacy laws such as GDPR and CAN-SPAM are the three cons of email marketing we list in the program, and all three come down to deliverability. It is the difference between a list of 5,000 people and a list of 5,000 addresses.

Key takeaways

• Deliverability is earned before you press send: a verified domain, a warmed-up sender, a recognisable from-name and a clean list do most of the work.
• Permission is everything. Never buy a list, never import contacts who did not ask, and use double opt-in.
• The unsubscribe link protects you. Hiding it produces spam complaints, which hurt more than a lost subscriber.
• Spammy language, "FREE" and "ACT NOW" in capitals with exclamation marks, triggers filters and trains readers to ignore you.
• Tags, segments and groups let you send the right message to the right people, which is the long-term fix for low engagement.

What deliverability actually means

Deliverability is the share of your emails that reach the inbox rather than the spam folder or a bounce. Mailbox providers decide where a message lands by looking at who is sending it, whether that sender has been trusted before, how past recipients reacted, and what the message looks like. Every rule below feeds one of those judgements.

The 10 rules

1. Send from a verified domain. Authenticate your own domain in your email platform so mailbox providers can confirm the email really comes from you. A free Gmail address sent through a marketing tool is the fastest route to the spam folder.
2. Warm up a new sending domain. A brand new domain that suddenly sends 5,000 emails looks like a spammer. Start with your most engaged contacts in small batches and grow the volume over a few weeks.
3. Send from a recognisable name. "Rana from Beirut Yoga Studio" gets opened. "Marketing Department" does not. The from-name is checked before the subject line.
4. Never send from a no-reply address. It tells the reader you do not want to hear from them, and replies are one of the strongest positive signals a mailbox provider sees. Use a real inbox and read it.
5. Never use a purchased list. Bought contacts did not ask for your email, they complain, they bounce, and the practice violates GDPR and CAN-SPAM. Most platforms will suspend the account.
6. Keep the list clean and remove bounces. Hard bounces are addresses that no longer exist. Remove them after every campaign, and remove people who have not opened anything in months after one re-engagement attempt.
7. Include a clear unsubscribe link, and never hide it. It is required by law and it is in your interest: a reader who cannot find it presses "report spam" instead, and complaints damage your reputation with every mailbox provider at once.
8. Avoid spammy language. All-caps words, rows of exclamation marks, "FREE", "ACT NOW" and "LIMITED TIME" are patterns filters were built to catch. Write a subject line under 50 characters that sounds like a person.
9. Do not send to cold lists without warming them up. A list you have not emailed in a year is cold, even if every contact opted in. Reintroduce yourself with a short, low-pressure email before sending offers.
10. Collect every contact with permission, and use double opt-in. Double opt-in asks the subscriber to confirm from their inbox before joining the list. It filters out typos and bots, and everyone who remains wants to be there.

Permission and list hygiene: the two habits behind the rules

Half the checklist reduces to one principle: only email people who asked, and stop emailing people who stopped caring. That means four sources of contacts and no others: manual entry of people you know, a CSV or Excel upload of contacts who gave permission, an app integration such as a website form connected to your platform, and embedded sign-up forms. On Squarespace, the built-in connection (Form Settings, then Storage, then Connect Mailchimp) adds every submission to your audience automatically, with double opt-in as a setting.

Hygiene is the second habit. After each send, remove hard bounces. Every quarter, find subscribers with no opens, send them one "we miss you" email, and remove anyone who does not respond. A smaller, engaged list gets better inbox placement than a large list of silent addresses, so pruning is maintenance, not loss.

Choosing an email platform

The platform does not fix bad habits, but the right one makes good habits easy. These are the five we compare in class; plans and limits change, so check each pricing page.

Platform	Best for	Free plan (at the time of writing)
Mailchimp	Beginners and small businesses; the platform we use in the program	Free plan for small lists with basic templates and limited automation
Brevo	Combining transactional and marketing emails	Free daily sending allowance
ConvertKit	Creators and bloggers	Free tier for smaller lists
Klaviyo	E-commerce, especially Shopify stores	Free tier for small lists
HubSpot	CRM plus email marketing together	Limited free tier

For a cafe, a clinic or a consultant starting from zero, Mailchimp's free plan covers audience management, a drag-and-drop builder, a journey builder, analytics, and integrations with Squarespace, Shopify and WordPress. Paid tiers unlock A/B testing and advanced automation and segmentation as the list grows.

Tags versus segments versus groups

Engagement is the deliverability signal you control most directly, and you raise it by sending fewer, more relevant emails. Four terms in Mailchimp make that possible.

Term	What it is	Who sets it	Example
Audience	Your entire contact list in one place	You, once	All subscribers
Tag	A label you assign by hand or through a form or integration	You	"VIP", "Lead", "Client", "Event Attendee"
Segment	A saved, rules-based filter that updates itself	You define the rule	"Opened the last 3 emails" or "Located in Beirut"
Group	A category the subscriber picks on a sign-up form	The subscriber	"I'm interested in: Services / Products"

Use one audience. Tag contacts by source and status as they arrive, build segments for behaviour such as engaged readers or past buyers, and let groups capture what subscribers say they want. Then send the promotion to the buyers, the educational series to the leads, and the re-engagement email only to the silent ones. Each send reaches fewer people and gets a higher open rate, which is what mailbox providers want to see.

Merge tags finish the job. A merge tag such as |FNAME| pulls a field from the contact record into the subject line or body, so "Hey |FNAME|, here's your exclusive offer" arrives as "Hey Sarah, here's your exclusive offer". Personalised subject lines are opened more, and opens are engagement.

Where this is taught

Deliverability, the Mailchimp set-up and the tag and segment structure are week 8 of the Professional Digital Marketing Associate Diploma, where students import test contacts with tags and build a welcome journey for their own project. The journey itself is walked through in How to Build a Welcome Email Journey in Mailchimp.

Frequently asked questions

How do I know if my emails are going to spam? Watch the open rate by mailbox provider in your platform's reports; a sudden drop for Gmail or Outlook addresses only is the usual sign. Send test emails to your own accounts on each provider, and check that your domain is authenticated.

Is it legal to email people in Lebanon and the Gulf without opt-in? Treat permission as mandatory everywhere. Your platform's terms require it regardless of local law, GDPR applies the moment a European resident is on your list, and unsolicited email produces the complaints that sink deliverability.

How many emails is too many? There is no fixed number; the signal is unsubscribes and complaints rising while opens fall. A monthly newsletter plus automated journeys triggered by behaviour is a safe pattern for most small businesses.