The Newsletter Deliverability Checklist: 12 Checks Before Your Next Send

Deliverability advice usually arrives as a 4,000-word essay when what you need is a list you can actually run down before a send. Here's the list. Twelve items: the first five are one-time setup, the middle four are habits, the last three are monitoring. Each one says what to do, how to verify it's done, and how often to revisit it.

A note on stakes first. Since February 2024, Gmail and Yahoo enforce hard requirements on bulk senders (roughly, 5,000+ emails/day to Gmail — but the practices apply at any size): authenticated email via SPF, DKIM, and DMARC; one-click unsubscribe; and a spam complaint rate under 0.3%. These aren't optimizations anymore. Miss them and your mail gets throttled, junked, or rejected.

Setup (do once, verify twice a year)

1. Send from a domain you own

Not yourname@gmail.com through an ESP, and not the ESP's shared domain. Your own domain — yourname.com or a subdomain like mail.yourname.com — is where your sending reputation accrues. On a shared domain, you inherit the behavior of every other sender on it; on your own, you inherit only your own history, and it moves with you if you ever switch ESPs.

Verify: look at the From address and the technical headers of your last issue. If the authenticated domain isn't yours, fix this first; items 2–4 depend on it.

2. SPF

SPF is a DNS record listing which servers may send email for your domain. Your ESP gives you the exact record to add.

Verify: send yourself an issue in Gmail, open Show original, and look for SPF: PASS. Or check the domain in a tool like MXToolbox.

3. DKIM

DKIM adds a cryptographic signature to each message; receiving servers check it against a public key in your DNS to confirm the mail is really from you and unaltered. Again, your ESP provides the DNS records — this is usually two or three CNAMEs added in ten minutes.

Verify: same Show original view: DKIM: PASS, signed by your domain (not the ESP's).

4. DMARC

DMARC ties SPF and DKIM together and tells receivers what to do when they fail. The minimum viable record is a TXT record at _dmarc.yourdomain.com:

``` v=DMARC1; p=none; rua=mailto:you@yourdomain.com ```

p=none satisfies the Gmail/Yahoo minimum and mails you aggregate reports about who's sending as your domain. Once you've watched reports for a while and everything legitimate passes, tightening to p=quarantine protects your domain from spoofing.

Verify: dig TXT _dmarc.yourdomain.com, or any free DMARC checker.

5. One-click unsubscribe

Gmail and Yahoo require bulk mail to include one-click unsubscribe — technically, List-Unsubscribe and List-Unsubscribe-Post headers, which produce that "Unsubscribe" link Gmail shows next to the sender name. Every serious ESP adds these automatically; your job is to not defeat them.

Verify: open your issue in Gmail and confirm the Unsubscribe link appears in the header area. And never bury or remove the in-body unsubscribe link either — an easy exit is what keeps people from hitting "Report spam," which costs you far more than an unsubscribe does.

Habits (every send, or every month)

6. Keep complaints under 0.3%

The 0.3% spam-complaint threshold is Gmail's published line for bulk senders; sustained rates above it damage placement across your whole list. Complaints usually spike for mundane reasons: emailing a list that hasn't heard from you in months, a sudden change in content or frequency, or subscribers who never clearly opted in.

Verify: Google Postmaster Tools (item 10) reports your actual complaint rate.

7. Clean your list

Every address that hard-bounces should be removed immediately (ESPs do this) — and, less obviously, so should subscribers who haven't opened anything in ~6 months, after one honest "should we part ways?" email. Sending to the disengaged drags down the engagement signals that mailbox providers use to judge you for everyone else. Shrinking your list to grow your reach feels wrong and works anyway.

Cadence: quarterly.

8. Use confirmed (double) opt-in

A confirmation click filters out typos, bots, and people who didn't really mean it — the exact populations that later bounce or complain. You'll grow slightly slower and deliver dramatically better.

9. Send consistently

Mailbox providers build a profile of your sending pattern. A steady weekly send from the same domain is a recognizable, trusted pattern. Six silent weeks followed by three sends in five days looks like something else. If you take a long break, warm back up: engaged segment first, then everyone.

Monitoring (the part everyone skips)

10. Set up Google Postmaster Tools

Free, ten minutes, Gmail-only, and the closest thing to an official dashboard: domain reputation, spam complaint rate, authentication success, delivery errors. It's a lagging indicator — by the time reputation dips, you've had a problem for a while — but a monthly glance catches slow rot.

11. Check blocklists occasionally

Rare for newsletter senders on reputable ESPs, but worth a two-minute MXToolbox blacklist check on your domain once a quarter, and immediately whenever deliverability suddenly craters.

12. Watch actual placement, not just opens

Everything above manages inputs. The output — where your email actually lands — is invisible in your ESP dashboard, because "delivered" includes the spam folder and the Promotions tab. The two direct checks:

• Open rate by provider: if your Gmail cohort's opens fall off a cliff while Outlook holds steady, Gmail placement changed. Check after every send; it's one segment view.
• Seed inboxes: your own subscriber accounts at Gmail, Outlook, and Yahoo. Subscribe them to your newsletter, and after each send note where the issue landed — inbox, Promotions, or spam. This is the only method that shows real placement at real providers, and it's the first thing a deliverability consultant sets up. The catch is discipline: it only works if you check every send, because the value is catching the week things flip.

The one-line version

Authenticate a domain you own, make leaving easy so nobody hits "spam," send steadily to people who actually open you, and check placement from the recipient's side — because no dashboard will tell you when it changes.

That last item is the one we kept failing to do by hand, which is why we're building Newsletter Health Check: seed inboxes at Gmail, Outlook, and Yahoo that subscribe to your newsletter, a placement report for every issue, and an alert the moment placement flips. (And if your newsletter lives on Substack, Newsletter Health Check does the equivalent watchdog job for Google indexing.) Both are in waitlist stage — join here if you want the monitoring without the chore.