There are a number of possible causes for "Undeliverable Mail" notifications.
Email address does not exist
- The email address does not exist.
- The email address no longer exists.
- The email address has been accidentally mistyped.
Message exceeds the size limit
For messages with large file attachments, we recommend using an alternative non-email upload method such as OneDrive or Dropbox, as email systems are not designed for large file transfers.
Please note the size limit applies to not only attachments, but also includes the message data.
Message has been blocked by the recipient
A mail filtering policy may have rejected the message at the recipient's end. In this case, we recommend contacting the recipient's system administrators to whitelist your email address.