When you’re facing incoming email issues on a cPanel or similar hosting server, there are several key areas you should investigate. Here’s a structured troubleshooting checklist:

✅ 1. DNS and MX Records

• Check if MX records point to the correct mail server (e.g., mail.yourdomain.com).
• Use tools like MXToolbox to verify DNS propagation and configuration.
• Ensure no conflicting A or CNAME records for the mail subdomain.

✅ 2. Mail Server Logs

Check these log files for errors:

• /var/log/exim_mainlog → Main Exim mail delivery log
• /var/log/exim_rejectlog → Shows rejected emails
• /var/log/exim_paniclog → For critical Exim errors

Use:

tail -f /var/log/exim_mainlog

✅ 3. Firewall and Port Access

• Confirm port 25 (SMTP), 110/995 (POP3), and 143/993 (IMAP) are open.
• Check CSF or any external firewall blocking mail ports.

✅ 4. Email Account Configuration

• Check if the email account exists in cPanel.
• Ensure mailbox is not full and the domain is active.
• Look for any email filters or forwarders that could be affecting delivery.

✅ 5. Spam or Blacklist Issues

• Check if your domain/IP is blacklisted.
• Ensure SPF, DKIM, and DMARC records are correctly configured.

✅ 6. Check Email Routing in cPanel

• In cPanel → Email Routing, ensure it’s set to the correct mode:
  • Local Mail Exchanger if mail is hosted locally.
  • Remote Mail Exchanger if using third-party services like Google Workspace.

✅ 7. Disk Space

• Ensure the hosting account or server isn’t out of disk space.

df -h

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✅ Incoming Email Issue Checklist – TechSpark IT Solutions

🔹 1. Check DNS & MX Records

• Verify MX records point to correct mail server (e.g., mail.domain.com)
• Confirm MX priority is correct
• Use: dig domain.com MX +short or online tools like MXToolbox
• Ensure A record for mail server exists

🔹 2. Examine Mail Logs (Exim)

tail -f /var/log/exim_mainlog
tail -f /var/log/exim_rejectlog
tail -f /var/log/exim_paniclog

• Look for reject reasons like “550”, “relay not permitted”, etc.

🔹 3. Check Firewall & Ports

• Ensure ports 25, 465, 587 (SMTP), 110/995 (POP), 143/993 (IMAP) are open
• Check CSF: csf -g <IP> to see if IP is blocked
• Temporarily disable CSF to test: csf -x

🔹 4. Validate Email Account

• Confirm email exists under cPanel > Email Accounts
• Mailbox quota not exceeded
• No custom filters or forwarders blocking mail

🔹 5. Check Email Routing

• Go to cPanel > Email Routing
• Should be “Local Mail Exchanger” for local hosting
• Set to “Remote Mail Exchanger” for Google/Microsoft mail

🔹 6. Blacklist / Spam Configuration

• Check if your IP/domain is blacklisted – use MXToolbox
• Verify SPF, DKIM, DMARC:

dig +short TXT domain.com

• Ensure emails are not getting flagged by spam filters

🔹 7. Check Disk Usage

df -h

• Ensure no partitions (especially /home, /var) are 100% full

🔹 8. Test with External Sender

• Send test email from Gmail, Outlook, etc.
• Confirm NDR (bounce) or missing silently