Troubleshooting
SMTP auth fails with Gmail
Gmail rejects regular account passwords for SMTP. Enable 2-step verification on the Google account, then generate an App Password at myaccount.google.com -> Security -> 2-Step Verification -> App Passwords. Use the 16-character generated password in the OMailer connection, not your Gmail login password.
Microsoft 365 sends fail with SMTP AUTH disabled
Microsoft 365 disables SMTP AUTH by default per mailbox. Open Exchange Admin Center -> Recipients -> Mailboxes -> select the mailbox -> Manage email apps -> enable Authenticated SMTP. Wait a few minutes for the change to propagate.
Amazon SES sends only reach addresses you control
New SES accounts are in sandbox mode. From the SES console, go to Account dashboard -> Request production access. You must verify your sending domain and request a sending limit increase before SES will deliver to arbitrary recipients.
Cron events never run, campaigns stay scheduled
WordPress cron runs only when your site receives traffic. For reliable sending, disable WP cron by adding define( 'DISABLE_WP_CRON', true ); to wp-config.php, then add a real system cron that hits wp-cron.php every minute:
* * * * * curl -s https://yoursite.com/wp-cron.php?doing_wp_cron > /dev/nullVerify scheduled events with wp cron event list from WP-CLI.
Open/click tracking shows zero on all campaigns
Check that om_settings['track_opens'] and om_settings['track_clicks'] are true (Settings -> Tracking). Opens require the tracking pixel to load, which is blocked by most ESPs scanning links and by privacy-focused mail clients (Apple Mail Privacy Protection). Clicks are tracked via redirect through /omailer-click/?u= and are more reliable. If both stay zero, check that the unsubscribe page exists (slug omailer-unsubscribe) and that rewrite rules are flushed (visit Settings -> Permalinks and save).
Bounce rate climbs after import
If you imported an old list, run wp omailer suppression import bounces.csv first so known-bad addresses are skipped. During IP warmup, OM_IPWarmup auto-pauses the schedule when bounce rate exceeds 2%. Fix the underlying list quality (re-verify addresses) before resuming.