Deliverability Best Practices
Improve your email deliverability and keep your sender reputation healthy.
Deliverability is the measure of how reliably your emails reach your subscribers' inboxes rather than their spam folder or being rejected outright. Good deliverability depends on a combination of technical configuration, list quality, and sending behavior — not just having a verified domain.
What affects your sender reputation
Email providers (Gmail, Outlook, Apple Mail, etc.) score every sender on a reputation scale. A high reputation means your emails land in the inbox. A low reputation means they land in spam, or worse, are rejected at the server level. The main factors are:
- Bounce rate — How often you send to addresses that don't exist or have blocked you. High bounce rates signal poor list hygiene.
- Spam complaint rate — How often recipients click "Mark as spam." Even a small number of complaints hurts your reputation significantly. Gmail treats a complaint rate above 0.1% as a warning sign.
- Engagement rate — Whether recipients open and click your emails. Low engagement tells providers your content is unwanted.
- Sending consistency — Sudden large spikes in volume look suspicious. Ramping up volume gradually is safer.
- Authentication — Whether your domain has valid DKIM and SPF records. Unauthenticated email is automatically treated with more suspicion.
Distill automatically handles bounces and complaints via AWS SES and SNS webhooks. When an address hard-bounces or a subscriber marks an email as spam, Distill immediately suppresses that address to protect your reputation.
Maintain a clean subscriber list
The single most impactful thing you can do for deliverability is to send only to people who want your emails.
Use confirmed opt-in. When someone subscribes via your signup form, Distill sends them a confirmation email. Only confirmed subscribers receive your newsletters. This prevents typos and fake sign-ups from entering your list.
Remove inactive subscribers periodically. If someone has not opened or clicked any of your last 10-15 issues, they are unlikely to engage in the future. Consider sending a re-engagement email ("Still interested? Click here to stay subscribed") and then unsubscribing those who don't respond.
Never use purchased lists. Sending to purchased or scraped lists is one of the fastest ways to destroy your sender reputation. These addresses have not consented to receive your emails, bounce at high rates, and generate spam complaints. Distill's Terms of Service prohibit sending to purchased lists.
Respect unsubscribes immediately. Distill processes unsubscribe requests instantly and ensures unsubscribed addresses are never emailed again.
Sending habits that improve deliverability
Send consistently. If you send a weekly newsletter, send it on roughly the same day every week. Consistency reinforces that your domain is legitimate. Sudden gaps of weeks or months followed by a large send spike can trigger spam filters.
Write subject lines that set accurate expectations. Misleading or clickbait subject lines generate high open rates initially, but also high spam complaint rates when readers feel tricked. Write subject lines that describe what is actually in the email.
Avoid spam trigger words in subject lines. Words like "FREE," "URGENT," "WINNER," and "LIMITED TIME OFFER" are associated with spam. They do not automatically cause filtering, but they contribute to spam scores. Use clear, honest language instead.
Keep your HTML clean. Emails with broken HTML, missing alt text on images, or unusual character encoding score higher on spam filters. Distill generates clean HTML from your newsletter templates.
Monitor your metrics in Distill
After each issue sends, Distill shows per-issue metrics on the issue detail page:
- Open rate — Percentage of delivered emails that were opened.
- Click rate — Percentage of delivered emails that had at least one link clicked.
- Bounce count — Number of addresses that rejected your email.
- Unsubscribe count — Number of people who unsubscribed after receiving this issue.
Track these over time. A sudden drop in open rates or spike in bounces is an early signal that something needs attention.
What triggers a sending suspension
Distill monitors key thresholds on behalf of AWS SES:
- Bounce rate above 5% — Distill will warn you and may pause sending.
- Complaint rate above 0.1% — Distill will warn you and may pause sending.
- Hard violation — If your account's aggregate bounce or complaint rate exceeds AWS SES limits, your sending access may be temporarily suspended.
If your sending access is paused, you will receive an email from Distill explaining the reason. To recover:
- Identify and remove the addresses causing the issue (export your subscriber list, review recent bounces).
- Clean your list before attempting to resume.
- Contact support at support@distill.ink to request review and reactivation.