The email deliverability checklist for SaaS founders (2026)

Deliverability problems feel mysterious, but fixing them is mostly a sequence of concrete, checkable steps. Work through this list top to bottom. The early items are foundations; the later ones are what actually move you from Promotions into the primary inbox.

1. Use a real sending domain, not a free mailbox

Send from your own domain (mail.yourapp.com or yourapp.com), never from a generic @gmail.com or @outlook.com address. You can't build or control reputation on a domain you don't own, and providers will not let you authenticate one.

2. Set up SPF, DKIM, and DMARC

• SPF: publish a TXT record authorizing your provider's servers to send for your domain.
• DKIM: enable signing in your email provider and add the public key records they give you.
• DMARC: start with a monitoring policy (p=none) and a reporting address, then tighten to quarantine once you've confirmed mail passes.

These prove you're authorized to send. They are mandatory, but they are the floor — not the strategy.

3. Separate transactional and marketing streams

Send password resets, receipts, and welcome emails from a different subdomain than newsletters or promotions. A marketing blast that triggers spam complaints should never be able to poison the reputation of your critical transactional mail.

4. Warm up the domain gradually

Don't go from zero to ten thousand emails overnight. Ramp volume over days or weeks so providers see a natural growth curve rather than a sudden spike that looks like a compromised account.

5. Write mail that looks personal, not bulk

• Send from a real human name and a reply-friendly address — never no-reply@.
• Keep welcome emails plain-text or lightly styled; image-heavy templates scream 'marketing'.
• Use the recipient's name and avoid spam-trigger phrasing and excessive links.

6. Generate engagement — especially replies

This is the step almost everyone skips, and it's the one that compounds. Ask new users to reply to your first email. A reply is the strongest trust signal a provider can see, and it lifts inbox placement for your entire domain. The best moment to ask is immediately after signup, when intent is highest.

7. Monitor and prune

• Watch bounce rates and remove invalid addresses quickly — high bounces wreck reputation.
• Honor unsubscribes instantly and make them easy to find.
• Read DMARC reports for unexpected sources sending as your domain.

Where ReplyBoost fits

Steps 1 through 5 are one-time setup. Step 6 — engagement — is ongoing, and it's exactly what ReplyBoost automates. Connect your provider, write one nudge, and every new signup is asked to reply, turning the hardest checklist item into something that runs itself.