Use a structured check before changing multiple email settings at once.
If you cannot send
- Sign in to Webmail and send a test message. If Webmail works, focus on the external mail application's settings.
- In Email Accounts → Connect Devices, compare the application's outgoing hostname, username, encryption method, and SMTP port with cPanel's recommended values.
- Confirm SMTP authentication is enabled and uses the full email address and current mailbox password.
- Use Track Delivery to inspect the result when the message appears in the report.
- Review Email Deliverability for DKIM/SPF/DMARC warnings if remote systems reject or distrust messages.
If you cannot receive
- Check Webmail first. If the message is present there, the problem is normally mail-client synchronization or configuration.
- Check Spam/Junk and any custom filters or forwarding rules.
- Verify that the mailbox is not at its storage limit.
- Review Email Routing and the domain's MX design if mail is supposed to be delivered locally.
- Use Track Delivery to determine whether the server delivered, deferred, rejected, or filtered the message.
Change one variable at a time and retest so you can identify the actual cause.