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Relaying denied means the mail server refused to send a message for you. It is not an outage. The usual causes are missing SMTP authentication, the wrong username, or a per-hour send limit. Use the full mailbox address on port 587 or 465 with TLS so the SMTP relay will accept the mail.
Authenticate with the mailbox on port 587 or 465
Set the SMTP username to the full mailbox address, such as [email protected]. Use that mailbox password, not the main cPanel password. Connect on port 587 with STARTTLS, or on port 465 with implicit TLS. Roundcube already uses these settings, so if webmail sends successfully, the account itself can send.
Port 25 from a home or office laptop is often blocked by the residential ISP. That can look like a timeout even though our servers are fine. Change the client to 587 or 465 with TLS before you treat it as a relay problem on our side.
When a send limit is the cause
Shared hosting accounts have per-hour send limits so a compromised form cannot flood the network. A contact form that emails on every bot submission will hit the cap and start returning errors. That behavior is intentional. If you need a higher limit for real traffic, such as order receipts after a launch, open a ticket and describe the volume. Large marketing campaigns usually belong on a dedicated email service so they do not share fate with password resets and notices.
Check the form before you ask for a higher limit
If a mailbox that used to work suddenly fails, and the logs show many messages to random addresses, do not raise the limit first. Change the mailbox password, then find the WordPress plugin, theme, or script that is leaking or abusing the SMTP settings. Raising the cap on a compromised form is a common path to an IP reputation problem.
In short, send with mailbox credentials on 587 or 465 and TLS enabled. Ask us to raise a send limit only after you are sure the traffic is legitimate. Port 25 from a laptop is usually an ISP block, and relaying denied is a refusal, not a server outage.
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