Delivery Status Notifications

Envelope-level rejections

Whenever an email is bounced during an SMTP transaction, we return an error code (which includes descriptive text) to the sending server to explain the situation. These bounce messages should give the administrators of the sending domain all the information they need to correct the issue causing their email to be blocked.

You can see the various bounce messages by searching in the communication logs.

Content-level rejections

Messages that aren't blocked during the SMTP transaction still run the risk of being blocked during our content-level verifications. Among all the quarantined messages, messages with a spam score of 5.0 or less are the ones with the highest likelihood of being legitimate. We automatically send a detailed Delivery Status Notification message to senders of these messages.

The senders will be directed to this page which offers the possibility for the sender to argue the legitimacy of their email. When filled out, this False Positive request is passed on to our team where it will be manually analyzed by a member of our technical team. Corrective actions can be taken such as releasing the message, adding the sender to the allow list, or taking corrective action on our filters as needed.

Banned files

Whenever an email with a score of 5.0 or less is blocked due to a banned file, a different message is sent to the sender to suggest they use another method to send their file. There is no interactive page associated with these emails as we never release messages with banned files.