No bounce, no delivery.
FIRST, CONFIRM IT LEFT
cPanel > Track Delivery. Search for the recipient address.
Success means the receiving server accepted it. The message is in their spam folder or was filtered on their side. The problem is not at our end.
Failed means it was rejected, and the reason is shown.
Nothing at all means it never left, which points at your mail client.
IF TRACK DELIVERY SHOWS SUCCESS
Ask the recipient to check spam and to whitelist your address.
Check SPF and DKIM under cPanel > Email Deliverability. Well-authenticated mail is filtered far less.
IF IT SHOWS DEFERRED
The receiving server asked for a retry. Usually greylisting, which adds minutes to a first message and then stops.
IF NOTHING APPEARS
The message never reached the server. Check the client's Sent folder and its outbox.
Check outgoing authentication is configured.
FOR APPLICATION MAIL
If your website sends the mail, configure SMTP rather than using the default PHP mail function.
