Start with one webmail test
Open Roundcube for the mailbox's assigned UKC server and sign in with the complete email address. Send one message to an unrelated address such as Gmail or Outlook, then reply to it. If webmail works, the mailbox and UKC mail service are normally healthy and the problem is likely limited to the mail app or device.
Identify the scope
Check what works before changing settings
- Confirm whether every mailbox on the domain is affected or only one address.
- Try a second device or network and note whether Roundcube opens.
- Test sending and receiving separately using an external address you control.
- Check whether failure affects every recipient or only Gmail, Microsoft or one organisation.
- Copy the complete bounce or error, including its status code and time.
If webmail works
Correct the device settings without deleting the account
Use the assigned UKC server hostname from the hosting welcome email, such as ukc12.uk. The username is the complete email address. Use IMAP port 993 with SSL/TLS and SMTP port 465 with SSL/TLS; port 587 with STARTTLS is the fallback. Outgoing authentication is required.
Do not remove the account from a device until you know whether messages are stored only on that device. Correct the server, port, encryption, username and password first.
Outlook settings Apple Mail settingsIf webmail fails
Check the mailbox, subscription and domain route
- Confirm the mailbox and its hosting or email service are active in the Client Area.
- Check mailbox and subscription storage in Plesk. A full mailbox can reject new mail.
- Confirm the domain's MX records still route mail to the intended UKC server. Website and email can use different providers.
- Reset the mailbox password in Plesk if neither Roundcube nor the device accepts it.
Read the symptom
Use the result to choose the next action
- Receiving works; sending fails
- Check SMTP authentication, port and encryption. See sending troubleshooting.
- Only one provider rejects mail
- Keep the bounce. It may identify reputation, policy, SPF/DKIM or recipient filtering.
- Certificate-name warning
- Use the assigned UKC hostname, not a raw IP or
mail.your-domain. - Forwarded mail is absent
- Confirm the forwarder and MX route, then check the destination's junk folder.
A useful test produces a clear result
You should know whether Roundcube works, whether both directions work, how many mailboxes are affected and the exact error. That is often enough to self-fix the problem or let support act without another round of questions.
Still unable to send or receive?
Send the mailbox address, domain, assigned UKC server, time tested, whether Roundcube works, affected devices, sending/receiving results and the complete bounce or screenshot. Never include the mailbox password.
Ask the Email team