It might happen in a campaign that mails get rejected, blocked or not delivered. You can identify problems in mail delivery at two sections in LUCY:
The mail log can be located under “support/service logs”:
The error log in a campaign can be located at the bottom of the overview page in that specific campaign:
If a mail receives a smtp error message within the campaign, you can see the details here. The errors displayed in this log are the ones LUCY receives from the remote SMTP server.