Orders placed in ACME automatically trigger a confirmation email to the Order Contact via SendGrid. SendGrid handles the email triggered by ACME until it reaches the recipient's email server. Once it is connected to that email server, the customer's email provider handles final delivery to their inbox (or spam box, or other filters; see this SendGrid article about Email messages with the “Delivered” status are not received).

An order's email confirmation delivery status can be viewed on the "Email Status" tab of the Order Summary (set in Administration>Email when SendGrid tracking is turned on):

For more information about resending order confirmation emails, please see our guide on Sending an Email Confirmation for an ACME Order.

SendGrid Statuses and their Meanings

StatusAdditional Info
ProcessedMessage has been received and is ready to be delivered.
DeliveredMessage has been successfully delivered to the receiving server. This status does not guarantee that the email was placed in the recipient’s inbox.
OpenedRecipient has opened the HTML message. You need to enable Open Tracking for getting this type of event (set in Administration>Email when SendGrid tracking is turned on).
DeferredRecipient’s email server temporarily rejected message (sometimes called a soft bounce). SendGrid will continue to attempt delivery for 72 hours; after 72 hours, the deferral turns into a block.
DroppedThis informs your system when an email has been dropped or blocked (for example, if the account has unsubscribed previously, or a spam filter blocks it).
BouncedReceiving server could not or would not accept message. Bounces often are caused by outdated or incorrectly entered email addresses.
Spam ReportRecipient marked message as spam.
UnsubscribeIndicates that an email has unsubscribed from mailings from your organization.
If click tracking is enabled, this status indicates that the recipient clicked on a link within the message. Click tracking is not available with ACME-generated emails.

Further Reading