Checking whether a customer has received a message or not is easy in Horizon. To do so, find their contact record and edit it.
Scroll down to the 'Contact activity' section. Here you can see all messages they have been sent. You'll see all but two messages here. Loyalty customers will not see the activation email or the reset password email. However the 'Welcome to the loyalty scheme' email will show, as well as the 'Your password has been reset' email.
In the 'Contact activity' section, there is a 'Status' field, which will tell you if the message sent or not.
'Success' means it was sent successfully. This means it's reached their email provider (e.g. Hotmail, Gmail, a work domain, etc). Once it gets to that point, we can't see what happens to it, as it's left our service boundary.
Ensure you ask the customer to check their spam folder. If that doesn't work, they would need to follow up with their email provider. The email provider will be able to check the system and see what happened to the message (ensure you give the customer the date/time the message was sent).
'Failure' means that the message failed to reach the customer. This can happen for a variety of reasons, such as the email provider was having delivery issues or the email address is invalid. If a message fails, the 'Contact activity' will state the reason for the failure.
In some cases, this is a temporary failure. However, the customer's email may have been blacklisted as a result (there will be a red circle by their email in the 'Channels' section of their contact record). If a customer is blacklisted, they will no longer be sent emails. Therefore you'd need to remove them from the blacklist. If you'd like to do this, please raise a support request with us. We can investigate this further and ensure it's safe to remove them from the blacklist. We can then get them removed from the blacklist.