Customers may not receive a campaign if:
Failed to send from Maestra (e.g., no subscription, expired consent, customer in Control Groups list, etc.);
Failed to deliver to the recipient's email server.
Both types of events can be found in campaign engagement tab.
You can also view the error reason and additional details there.
Campaign engagements and customers can be filtered by these reasons.
Find all undeliveries with the reason Mailbox full.
Find all send failures where the message could not be composed.
Find customers who had two or more undeliveries with the reason Recipient rejected email due to content for the last week.
