When email will not leave your mailbox or your website's contact form goes quiet, the cause is usually one of a handful of things: wrong SMTP settings in the mail app, a blocked port on your network, a sending limit, or a website using PHP mail without authentication. This guide tests each one in order.
Before you start
- Access to cPanel (open it from Services in the MdmHost dashboard).
- The full email address and its password.
- Any bounce message you received; codes are explained in Common email bounce errors.
Test from Webmail first
- Go to cPanel → Email → Email Accounts and click Check Email next to the account.
- Send a test to an outside address such as a Gmail account.
- If it arrives, the server is fine and the problem is in your mail app or network. If it doesn't, continue with Track Delivery below.
Check your mail app's SMTP settings
In Email Accounts → Connect Devices, cPanel shows the exact settings. The usual ones are:
| Setting | Value |
|---|---|
| Outgoing server | The server hostname from Connect Devices (or mail.yourdomain.com) |
| Port | 465 (SSL/TLS) or 587 (STARTTLS) |
| Authentication | On; username is the full email address |
Note: Many home and mobile networks block port 25. Never use port 25 in a mail app; use 465 or 587.
Use Track Delivery to see what happened
- Open cPanel → Email → Track Delivery.
- Search for the recipient address and look at the status icon and the Result column.
- A red failure shows the remote server's reason, for example a blocklisted IP, a rejected sender or a full mailbox at the other end.
Check sending limits and suspended mail
Hosting accounts have an hourly sending limit to protect the server's reputation. If a form or newsletter sent a burst of mail, new messages are deferred until the hour resets. A compromised password can also trigger suspended outgoing mail. Change the mailbox password and contact support if outgoing mail is suspended.
Fix email from WordPress and contact forms
Websites often send with PHP mail() from an address that doesn't exist, which receivers reject or mark as spam. Instead:
- Create a real mailbox such as
noreply@yourdomain.com. - Install an SMTP plugin (for example WP Mail SMTP) and set host, port 465 and the mailbox login.
- Set the form's From address to that mailbox, and put the visitor's address in Reply-To.
Check SPF, DKIM and DMARC
Missing authentication records make Gmail and Outlook reject or junk your mail. Open cPanel → Email → Email Deliverability and fix any record marked with a problem. If mail is sent but lands in junk, follow Fix emails going to spam.
Troubleshooting
- "535 Incorrect authentication data": wrong password or the username is not the full address. Reset the password in Email Accounts.
- Connection timed out on send: your network blocks the port; try 587 instead of 465, or another network.
- Certificate warning in the mail app: use the server hostname from Connect Devices, see email client certificate warnings.
- Webmail itself will not open: see Fix webmail login problems.