If a customer does not receive their gift card, it's either because the purchaser entered an incorrect email address, or the email was blocked by a spam filter, was placed in quarantine or some other filter set up on their email inbox.
If an email was not delivered due to an incorrect email address:
We mostly get notified by email servers if an email was rejected because of an incorrect email address or a full mailbox, etc... but we will need you to confirm the new email address at firstname.lastname@example.org and we will resend to the correct address.
The email is marked as 'delivered', but has not made it to an inbox:
Typically, in these circumstances we get confirmation that the email was accepted by the recipient's email server, but no email arrives in the inbox. It does not often happen, but it's infuriating for all involved if this is the case.
If you email us directly at email@example.com we will reply with a downloaded version of the gift card to them. Because of the simple fact that you are replying to an email they sent, the reply is almost guaranteed to make it to their inbox as a result.
Email is a tough delivery medium to work with thanks to spammers over the last 20 years. As a result, platforms like Not Forgotten cannot 100% know whether an email really made it to a user's inbox. We can sometimes tell if it was clicked on or opened, which is a good indication of inbox delivery, but it's also possible an email server accepts an email but just does not deliver it to an inbox.
Ultimately email is a fallible delivery method - it's entirely acceptable and correct for a mail server to accept an email because the 'to' address is correct and valid, and put it somewhere other than a user's inbox, like a spam folder or in quarantine. These things are rule based usually and email inboxes are configured in some weird and wonderful ways sometimes. In the end, sometimes we have to accept that an email does not make it to an inbox.
At Not Forgotten we monitor our email reputation with email service providers and have a very good relationship with them, so they tell us when an email gets outright rejected or actively marked as SPAM, but some more independent mail servers just say nothing back.