Help ensure your emails
hit the inbox
Stop guessing why your messages end up in spam. Follow this 26-point checklist to achieve technical compliance, enhanced sender reputation, and delivery success.
One Email Per Recipient
When sending to a mailing list, each recipient should receive their own individual email. Do not send single messages with a large number of recipients on the 'To:', 'Cc:', or 'Bcc:' lines.
Privacy & Compliance — Using 'To:' or 'Cc:' exposes recipient email addresses to everyone else on the list, which is a major privacy breach and a violation of data protection laws like GDPR.
Spam Filters — Mailbox providers (like Gmail, Outlook, AOL, Yahoo, etc.) are highly suspicious of single messages addressed to large numbers of recipients at once. This behavior is a hallmark of low-quality bulk mail and often leads to immediate rejection or placement in the spam folder.
Personalization — Professional delivery requires sending individual messages so you can personalize content (e.g., "Hi Name") and accurately track engagement or manage unsubscribes for each specific user.
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