Email will not send or arrive: troubleshooting

Establish the scope

Record the failed message's time, sender, recipient and any bounce error. Check whether the problem affects one app, one address or all messages. Do not send support screenshots containing your password.

Check in this order

1. Sign in to Roundcube and send a test to an external address. Ask for a reply. If webmail works, check the phone or Outlook IMAP and SMTP settings.
2. In cPanel Email Accounts, check mailbox status, quota and any restrictions. Also check the service's total disk usage.
3. If only sending from an app fails, verify the full email address as the SMTP username, the correct password and an encrypted port.
4. Open Track Delivery, if available. Search for the recipient and inspect the event at the relevant time.
5. For incoming mail problems, check the domain's active MX records. With external nameservers, make corrections where the authoritative DNS zone is managed.
6. For messages going to spam, review SPF and DKIM findings in Email Deliverability and the recipient's spam folder.

Interpret the result

Acceptance by the receiving server does not guarantee placement in the inbox. A temporary delivery error may trigger another attempt; a permanently rejected message usually needs to be sent again after the issue is fixed.

If the problem continues, open a support ticket with the details above and the error text. Redact message content and personal information that the investigation does not need. Do not experiment with MX changes when you intentionally use another email provider.