The Ultimate Email Deliverability Checklist

Everything you need to land in the inbox, not spam: SPF, DKIM and DMARC, bulk sender rules, list quality, content and monitoring in one practical checklist.

You can write the best email of your life, but if it lands in spam, it earns exactly nothing. Deliverability is the art and science of getting your emails into the inbox, and it’s the foundation every profitable list is built on. This checklist walks you through everything that matters, from DNS records to daily sending habits.

Deliverability vs. delivery: know the difference

Delivery means the receiving server accepted your email. Deliverability means it landed where people will see it: the inbox, not the spam folder or a forgotten tab. Your email platform might proudly report a high delivery rate while a large chunk of your mail quietly goes to spam. That’s why you need to look beyond the dashboard.

Part 1: Authentication (the non-negotiables)

Authentication proves to mailbox providers that you’re really you. Since 2024, Gmail and Yahoo have required bulk senders to authenticate their mail, and other providers reward it too. Treat these as mandatory.

SPF (Sender Policy Framework)

SPF is a DNS TXT record that lists which servers are allowed to send email for your domain. A basic record looks like this:

v=spf1 include:_spf.yourprovider.com ~all

• Have only one SPF record per domain. Multiple SPF records break it.
• SPF has a limit of 10 DNS lookups. Too many “include” statements can push you over.

DKIM (DomainKeys Identified Mail)

DKIM adds a cryptographic signature to your emails so receivers can verify the message wasn’t altered and was authorized by your domain. Your email platform generates the DKIM record; you add it to your DNS. Make sure you’re signing with your own domain, not only the platform’s shared domain.

DMARC (Domain-based Message Authentication, Reporting and Conformance)

DMARC tells receivers what to do when a message fails authentication, and it sends you reports. It also checks alignment: that the domain in your visible “From” address matches the domain verified by SPF or DKIM. Start with a monitoring policy:

v=DMARC1; p=none; rua=mailto:dmarc-reports@yourdomain.com

Once your reports show that all legitimate mail passes, you can gradually tighten the policy to p=quarantine and eventually p=reject to protect your domain from spoofing.

Part 2: Bulk sender requirements

Gmail and Yahoo introduced stricter rules for bulk senders in 2024. Even if you’re small today, build as if they apply to you:

• Authenticate with SPF, DKIM and DMARC, with alignment.
• One-click unsubscribe for marketing mail, using the List-Unsubscribe and List-Unsubscribe-Post headers, and honor requests promptly (within two days).
• Keep spam complaints low: stay well under 0.3%, and aim for under 0.1%.

Most reputable email platforms handle the unsubscribe headers for you. Your job is to authenticate your domain and send mail people actually want.

Part 3: List quality

Who you send to matters as much as how you send. Mailbox providers watch how recipients react.

For a deep dive, see our List Hygiene Handbook.

Part 4: Content and formatting

Content filters are smarter than old “spam word” lists, but content still affects how people react, and that affects deliverability.

• Match expectations. Send what people signed up for, at the frequency you promised.
• Balance text and images. Avoid emails that are a single big image.
• Limit links and avoid link shorteners, which are often associated with abuse.
• Use a recognizable from name and a clear, honest subject line.
• Include a plain-text version alongside HTML.
• Make unsubscribing easy. A hidden unsubscribe link often turns into a spam complaint.

Run your copy through the Spam Word Checker to spot pushy, hype-heavy phrasing before you hit send.

Part 5: Sending behavior and reputation

Your domain and IP reputation are built over time through consistent, positive sending.

• Warm up new domains and IPs. Start with your most engaged subscribers and increase volume gradually over a few weeks.
• Be consistent. Sudden spikes in volume look suspicious.
• Segment by engagement. Send more often to active readers, less often to quieter ones.
• Consider a sending subdomain (like news.yourdomain.com) to separate marketing reputation from your everyday business email.

Part 6: Monitoring

You can’t fix what you don’t measure. Keep an eye on these:

Metric	What it tells you	What to do if it’s bad
Spam complaint rate	How many people mark you as spam	Tighten targeting, clarify expectations, make unsubscribing easier
Bounce rate	Invalid or unreachable addresses	Clean the list, verify signups, fix form issues
Click rate	Real engagement	Improve relevance, segment, test calls to action
Open rate (with caution)	Rough trend only	Compare over time, not as an absolute truth
Domain reputation	How Gmail views your domain	Check Google Postmaster Tools regularly

Remember: Apple Mail Privacy Protection can register opens automatically, which inflates open rates. Use clicks, replies and conversions as your main engagement signals, and treat opens as a directional trend.

Troubleshooting: “My emails are going to spam!”

1. Check authentication. Are SPF, DKIM and DMARC all passing and aligned?
2. Check your complaint rate and domain reputation in Postmaster Tools.
3. Look at recent changes: new list import, sudden volume jump, new link domain?
4. Pause sending to inactive segments and send only to your most engaged readers for a while.
5. Review content: does it match what people signed up for?