You've been referred to this page because of a mail delivery failure. Given you've followed the link in the bounce, you didn't expect that so here is some advice on what might have caused your failure.
- Your sender or recipient isn't valid for this server – senders and recipients must be fully-qualified.
- Your message must be reply-able – your domain must publish MX or A records. Additional verification may also occur.
- Your message must observe the sending domain's SPF, DKIM and DMARC policies. Having valid SPF and DKIM don't influence your score - but this server does observe the sending domain's policies and does not send DMARC reports.
- Your server configuration must comply with email best practices including valid forward and reverse DNS for both the sending IP and HELO (if different).
- Your sending IP must not be on common, high reputation IP blacklists. No single listing will result in rejection, so if this is the cause you will be on several lists.
- The content of your message must not be excessively "spammy" or malformed.
- You should not be sending potentially dangerous attachment formats.
- Your message should not have suspicious characters in the headers.
- Your message should not use MIME Type message/partial.
If you believe your message was rejected in error please open a support request. Please provide as much information (including the bounce message) as possible.
If you have a secretinbox.net destination alias that is rejecting your mail, this is because your alias has been leaked and is being used for SPAM. You are, therefore, no longer allowed to send mail until you can establish a new alias. You may reach out using the support request form or any other contact method you have on file for me.