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# Why are some emails not being delivered?

If some emails are not being delivered from your campaigns and automations, the cause is usually one of these areas:

**1. Missing or Failed Authentication:** Emails without proper SPF, DKIM, or DMARC authentication may fail verification checks, causing recipient servers to reject or distrust them (Tools like **MXToolbox**, **DMARCly**, or similar DNS checkers can validate these records)

**2. Spam and Content Filters:** Email providers may block or redirect messages to spam due to suspicious content, excessive links, attachments, or formatting issues.

**3. Poor Sender Reputation:** A low-quality sender reputation caused by high bounce rates, spam complaints, or poor engagement can reduce email deliverability.

**4. Full Mailboxes:** The recipient’s inbox may be unable to receive new messages because their storage limit has been reached.

**5. Invalid Email Addresses:** Incorrect, outdated, or inactive email addresses can cause delivery failures and hard bounces.

**8. Automation or Campaign Configuration Issues:** Incorrect workflow rules, scheduling settings, audience filters, or sending limits can prevent emails from being sent.

**9. Suppression or Unsubscribed Contacts:** Contacts who opted out, bounced previously, or were added to suppression lists will not receive future emails.

**10. Poor List Quality:** Old or inaccurate contact lists increase bounce rates and negatively affect overall deliverability.