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Troubleshoot deliverability problems

Diagnose common issues like failing authentication, mail landing in spam, and high bounce rates.

Symptom​

A Broadcast underperforms in a way that points to a delivery problem rather than a content problem. Common signs:

  • Authentication warnings (SPF, DKIM, or DMARC) reported in the Broadcast's delivery details, or "unauthenticated" indicators shown by receiving mailboxes.
  • Messages landing in the Junk or Spam folder for subscribers who previously received mail in their inbox.
  • A sudden spike in bounces, or open rates dropping close to zero across a whole domain (for example, all subscribers at one company).

Likely causes​

Ranked from most to least common:

  1. Broken or missing authentication. Your sending domain's SPF, DKIM, or DMARC records aren't published correctly, so receivers can't verify the mail as yours.
  2. Reputation damage. A large send to stale or purchased addresses, or a jump in spam complaints, has lowered your domain or IP reputation.
  3. Content and list hygiene. Spam-trigger phrasing, heavy image-to-text ratios, or repeated sends to addresses that hard-bounced.
  4. Recipient-side blocking. A subscriber's mail server or corporate gateway is filtering or blocking your domain.

Fixes​

  1. Confirm authentication first. Verify that SPF, DKIM, and DMARC are published for your sending domain and are passing. Have your DNS administrator make any record changes (confirm the exact records and values in your account).
  2. Clean the list. Remove hard bounces and long-term non-openers, and confirm nothing is being sent to addresses already on the suppression list. See Manage the suppression list.
  3. Warm up gradually. After a reputation dip, resume with smaller, engaged segments and increase volume over several sends rather than all at once.
  4. Review content. Test the Edition against a spam-scoring check, balance images with real text, and avoid deceptive subject lines before re-sending the Broadcast.
  5. Isolate the affected domain. If only one recipient domain is impacted, ask that organization's IT team to allowlist your sending domain and address.

Still stuck?​

If authentication passes and hygiene is clean but delivery is still poor, gather the affected Broadcast, the recipient domains involved, and any bounce or rejection messages, then contact your account's support team so they can review reputation and sending logs.

Canonical terms: Author, Edition, Folder (Project Folder), Broadcast. See the Glossary.