Email deliverability

Deliverability is measured as the percentage of sent emails that land in the inbox. Even a perfectly written email is worthless if it never gets there.

Deliverability is not the same as delivery rate. Delivery rate counts the emails that did not bounce, meaning the receiving server accepted them. Deliverability counts the ones that then reached the inbox and not the spam folder. You want both to be high.

• Sender reputation

  Mailbox providers track how you send over time. High engagement, few complaints and few bounces build a good sender reputation; poor practices damage it.

• Authentication

  SPF, DKIM and DMARC prove your email is legitimate. Without them, mail is more likely to be flagged as spam.

• Content

  Spam filters read your subject line, body, links and images. Spammy language, too many links or misleading content trigger them.

• List quality and engagement

  Opens and clicks from people who want your email signal quality. Low engagement and spam complaints hurt.

• Infrastructure

  Your sending IP, domain reputation and setup affect how providers see you. At scale, dedicated IPs and a proper warm-up matter.

Authentication and setup

• Configure SPF, DKIM and DMARC

  Set up all three. They prove your mail is legitimate and protect your domain from spoofing.

• Send from a dedicated subdomain

  Send marketing from a subdomain such as mail.yourdomain.com, so problems there do not touch your main domain’s reputation.

• Warm up new IPs and domains

  Raise volume gradually over 2 to 4 weeks. Sudden high volume from a new source looks suspicious.

List management

• Use double opt-in

  Ask new subscribers to confirm their address. It keeps the list clean and keeps spam trap addresses out.

• Clean your list regularly

  Remove hard bounces immediately and consider removing anyone who has not engaged in 6 to 12 months. Inactive subscribers hurt your reputation. See bounce rate for more.

• Make unsubscribing easy

  Put a clear unsubscribe link in every email. People who cannot find it mark you as spam, which does far more damage.

Content

• Skip spam trigger words

  Words like “FREE”, “ACT NOW” and “LIMITED TIME”, strings of exclamation marks and all caps trigger filters. Write the way you would to a customer.

• Balance text and images

  Never send image-only emails. Keep at least 60% text and add alt text to every image.

• Write honest subject lines

  The subject should match the email. Misleading subjects drive complaints and erode trust.

Run a draft through the spam checker before you send to catch trigger words and formatting problems.