Roundcube vs a mail app

Roundcube is the webmail that runs on your hosting account inside cPanel. A mail app on your phone or computer connects over IMAP and shows a local view of that same mailbox. When mail seems missing on one device, open Roundcube first so you can tell whether delivery failed or the client is simply out of sync.

Check Roundcube before you touch the phone

In cPanel, open Email Accounts and choose Check Email for the mailbox. Sign in as that address and look for the message. If it is already there, delivery succeeded and the problem lives on the device. The app may use the wrong protocol, an old password, or a folder it never subscribed to. If Roundcube is empty as well, then check MX records, mailbox quota, and whether the sender received a bounce. You do not need to dig through Apple Mail or Outlook settings until webmail has spoken.

Deleting a folder in a client often only unsubscribes from it. The mail usually remains on the server, and Roundcube will still show INBOX and the other folders. Confirm what you see in webmail before you restore a full account backup you may not need.

Know which side your filters run on

Filters you create in Roundcube are server-side Sieve rules on this stack. They run even when the phone is off. Filters inside Outlook or Apple Mail stay on that device alone. A rule that files invoices into a local Outlook folder will never appear on the phone. A Sieve rule that moves them into INBOX.Invoices will show everywhere that uses IMAP. Mixing the two sides is a common reason people think the server is dropping mail.

What the mail app is for

Use the app for reading and sending while you are away from a browser. It is not the source of truth for the mailbox. Point it at your domain’s mail host with IMAP on port 993 and submission on 587, and use the mailbox password. If the app offers to “repair” the account by switching to POP, decline that change. If it wants to turn TLS off because a certificate name does not match, fix the hostname instead of disabling encryption.

Treat Roundcube as proof that the mailbox is healthy. Use the app for convenience on the go. When the two disagree, trust Roundcube and then correct the client. Quota and Trash still apply on the server, so a full mailbox will fail in both places until you free space.