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supportHi everyone, I am suddenly having issues with MailPoet on my WordPress 7.0 site. On my WordPress dashboard, I see the following error message: “Das Senden wurde wegen eines technischen Problems mit MailPoet pausiert: Kein gültiger API-Schlüssel angegeben.” (Sending paused due to a technical problem: No valid API key specified). Before this happened, I also noticed that my sender email address was suddenly unauthenticated. Here is what I have checked and done so far: When I log into my MailPoet.com account, everything shows up as green, valid, and fully authenticated. There are no alerts or issues listed in my account panel. I already tried re-entering and re-validating the API key in my WordPress MailPoet settings. After doing that, some of the previous error messages disappeared, but now this specific API key error keeps coming back and pausing my email queue again. Any help or advice would be greatly appreciated! Thank you!
Hello there @meike297 , Thank you for reaching out to us. Can you let me know the website connected to your MailPoet account? Looking forward to hearing back from you.
sure! Its meikereist.de I tried again several things, for example I deleted the mails which were stucked/paused. But its still not working. Thank You
Hi there @meike297 , Thanks for sharing your website domain. I can confirm the domain is successfully authenticated and there are no issues on your account. This is most likely an issue that happens when MailPoet’s scheduled key-validation task sees a different URL than the one your API key is registered to. Even though your key is valid on your MailPoet.com account, the cron task on your site may be resolving a slightly different URL (e.g., www vs. non- www , or an internal hosting URL), which causes the key to fail and sending to pause. The sender email becoming unauthenticated is a side effect of the key being invalidated. Here’s how to track down and fix it: Step 1: Enable logging to capture the mismatch Go to MailPoet → Settings → Advanced → Logging and set it to “Everything” . Then wait for the error to reoccur. Once it does, go back to MailPoet → Settings → Advanced and click “View Logs” . Look for entries labeled mss.ERROR: key-validation.failed — expand the truncated message (Cmd+click on Mac, Ctrl+click on Windows) and it will show you which URL was returned during the failed check. That’s the key clue. Step 2: Check for URL inconsistencies Compare the URL in the failed log entry against your actual site URL. Common causes: A mismatch between the WordPress Address and Site Address in Settings → General WP_SITEURL or WP_HOME constants set in your wp-config.php that differ from the database values — these constants also need to be defined before the line that loads wp-settings.php , otherwise cron may use an outdated database value A www vs. non- www discrepancy Your hosting provider triggering cron from an internal URL that differs from your public domain Step 3: Apply a workaround while you investigate Switching to server-side (Linux) cron bypasses the WordPress HTTP-based cron entirely, which avoids the URL mismatch during the key check. You can set this up by following this guide: https://kb.mailpoet.com/article/257-setting-the-server-side-cron-linux-cron If you’re unsure how to set up a cron job, your hosting provider’s support team can usually help with this — just share the guide above with them. Step 4: Re-authenticate your sender email Once the key stays valid after the changes, go to MailPoet → Settings → Basics and re-verify your sender email authentication. It likely reset when the key was invalidated. For more details, this MailPoet KB article covers the issue in depth: https://kb.mailpoet.com/article/398-what-should-i-do-if-my-mailpoet-key-is-deactivated-on-its-own
Hello! I don’t come further than Step 1. I did this and only found: [2026-06-10T12:07:38.537883+00:00] mss.INFO: key-validation.failed {“http_code”:401,”home_url”:” https://meikereist.de” ;,”key_type”:”mss”} {“free_plugin_version”:”5.28.1″,”premium_plugin_version”:”premium not installed”} or [2026-06-10T12:16:13.087423+00:00] mss.INFO: requests-curl.after_request {“headers”:”HTTP/1.1 401 Unauthorized\r\nDate: Wed, 10 Jun 2026 12:16:13 GMT\r\nContent-Type: application/json\r\nContent-Length: 25\r\nConnection: close\r\nWWW-Authenticate: Basic realm=\”API\”\r\nStrict-Transport-Security: max-age=31536000; includeSubDomains\r\n\r\nNo valid API key provided”,”curl_info”:{“url”:” https://bridge.mailpoet.com/api/v0/messages” ;,”content_type”:”application/json”,”http_code”:401,”header_size”:238,”request_size”:979840,”filetime”:-1,”ssl_verify_result”:0,”redirect_count”:0,”total_time”:0.087313,”namelookup_time”:0.000369,”connect_time”:0.007719,”pretransfer_time”:0.024226,”size_upload”:979566.0,”size_download”:25.0,”speed_download”:286.0,”speed_upload”:11219016.0,”download_content_length”:25.0,”upload_content_length”:979566.0,”starttransfer_time”:0.087249,”redirect_time”:0.0,”redirect_url”:””,”primary_ip”:”2a01:7e01:1::ac69:9259″,”certinfo”:[],”primary_port”:443,”local_ip”:”2001:608:e00:72::40:0″,”local_port”:41478,”http_version”:2,”protocol”:2,”ssl_verifyresult”:0,”scheme”:”https”,”appconnect_time_us”:24027,”connect_time_us”:7719,”namelookup_time_us”:369,”pretransfer_time_us”:24226,”redirect_time_us”:0,”starttransfer_time_us”:87249,”total_time_us”:87313,”effective_method”:”POST”,”capath”:””,”cainfo”:”/etc/pki/tls/certs/ca-bundle.crt”}} {“free_plugin_version”:”5.28.1″,”premium_plugin_version”:”premium not installed”} So I cannot see any email address…
Hello there @meike297 , Thank you for reaching out to us. Can you let me know the website connected to your MailPoet account? Looking forward to hearing back from you.
sure! Its meikereist.de I tried again several things, for example I deleted the mails which were stucked/paused. But its still not working. Thank You
Hi there @meike297 , Thanks for sharing your website domain. I can confirm the domain is successfully authenticated and there are no issues on your account. This is most likely an issue that happens when MailPoet’s scheduled key-validation task sees a different URL than the one your API key is registered to. Even though your key is valid on your MailPoet.com account, the cron task on your site may be resolving a slightly different URL (e.g., www vs. non- www , or an internal hosting URL), which causes the key to fail and sending to pause. The sender email becoming unauthenticated is a side effect of the key being invalidated. Here’s how to track down and fix it: Step 1: Enable logging to capture the mismatch Go to MailPoet → Settings → Advanced → Logging and set it to “Everything” . Then wait for the error to reoccur. Once it does, go back to MailPoet → Settings → Advanced and click “View Logs” . Look for entries labeled mss.ERROR: key-validation.failed — expand the truncated message (Cmd+click on Mac, Ctrl+click on Windows) and it will show you which URL was returned during the failed check. That’s the key clue. Step 2: Check for URL inconsistencies Compare the URL in the failed log entry against your actual site URL. Common causes: A mismatch between the WordPress Address and Site Address in Settings → General WP_SITEURL or WP_HOME constants set in your wp-config.php that differ from the database values — these constants also need to be defined before the line that loads wp-settings.php , otherwise cron may use an outdated database value A www vs. non- www discrepancy Your hosting provider triggering cron from an internal URL that differs from your public domain Step 3: Apply a workaround while you investigate Switching to server-side (Linux) cron bypasses the WordPress HTTP-based cron entirely, which avoids the URL mismatch during the key check. You can set this up by following this guide: https://kb.mailpoet.com/article/257-setting-the-server-side-cron-linux-cron If you’re unsure how to set up a cron job, your hosting provider’s support team can usually help with this — just share the guide above with them. Step 4: Re-authenticate your sender email Once the key stays valid after the changes, go to MailPoet → Settings → Basics and re-verify your sender email authentication. It likely reset when the key was invalidated. For more details, this MailPoet KB article covers the issue in depth: https://kb.mailpoet.com/article/398-what-should-i-do-if-my-mailpoet-key-is-deactivated-on-its-own
Hello! I don’t come further than Step 1. I did this and only found: [2026-06-10T12:07:38.537883+00:00] mss.INFO: key-validation.failed {“http_code”:401,”home_url”:” https://meikereist.de” ;,”key_type”:”mss”} {“free_plugin_version”:”5.28.1″,”premium_plugin_version”:”premium not installed”} or [2026-06-10T12:16:13.087423+00:00] mss.INFO: requests-curl.after_request {“headers”:”HTTP/1.1 401 Unauthorized\r\nDate: Wed, 10 Jun 2026 12:16:13 GMT\r\nContent-Type: application/json\r\nContent-Length: 25\r\nConnection: close\r\nWWW-Authenticate: Basic realm=\”API\”\r\nStrict-Transport-Security: max-age=31536000; includeSubDomains\r\n\r\nNo valid API key provided”,”curl_info”:{“url”:” https://bridge.mailpoet.com/api/v0/messages” ;,”content_type”:”application/json”,”http_code”:401,”header_size”:238,”request_size”:979840,”filetime”:-1,”ssl_verify_result”:0,”redirect_count”:0,”total_time”:0.087313,”namelookup_time”:0.000369,”connect_time”:0.007719,”pretransfer_time”:0.024226,”size_upload”:979566.0,”size_download”:25.0,”speed_download”:286.0,”speed_upload”:11219016.0,”download_content_length”:25.0,”upload_content_length”:979566.0,”starttransfer_time”:0.087249,”redirect_time”:0.0,”redirect_url”:””,”primary_ip”:”2a01:7e01:1::ac69:9259″,”certinfo”:[],”primary_port”:443,”local_ip”:”2001:608:e00:72::40:0″,”local_port”:41478,”http_version”:2,”protocol”:2,”ssl_verifyresult”:0,”scheme”:”https”,”appconnect_time_us”:24027,”connect_time_us”:7719,”namelookup_time_us”:369,”pretransfer_time_us”:24226,”redirect_time_us”:0,”starttransfer_time_us”:87249,”total_time_us”:87313,”effective_method”:”POST”,”capath”:””,”cainfo”:”/etc/pki/tls/certs/ca-bundle.crt”}} {“free_plugin_version”:”5.28.1″,”premium_plugin_version”:”premium not installed”} So I cannot see any email address…