Common Email Error Messages

Email problems typically fall into two categories:

1. Client-side configuration errors: Issues when setting up or using email clients (Outlook, Thunderbird, Apple Mail, etc.).
2. Server-side delivery errors: Indicated by bounce messages containing SMTP or Extended SMTP (ESMTP) error codes.

This guide combines practical troubleshooting for both. Use the sections below to match your exact error message.

How to Diagnose Your Email Issue

Before troubleshooting:

• Note the exact error message or copy the full bounce email (including headers if possible).
• Determine if the error occurs when sending/receiving in your email client (client config) or you received a bounceback message (SMTP code).
• Have cPanel access ready (to reset passwords, verify accounts, or check MX records).
• Know your full email address and domain.

Quick Recommendations for All InMotion Customers

• Always use SSL/TLS encryption for email connections.
• Username is always your full email address ([email protected]), never just the username or cPanel username.
• Outgoing SMTP server requires authentication using the same credentials as incoming.
• Use InMotion’s recommended settings (see below).

Recommended Email Client Settings for InMotion Hosting

Use these settings in Outlook, Thunderbird, Apple Mail, or any client:

Standard Secure Settings (Recommended)

Protocol	Server Name	Port	Encryption	Notes
IMAP	mail.yourdomain.com	993	SSL/TLS	Preferred for most users (syncs across devices)
POP3	mail.yourdomain.com	995	SSL/TLS	Downloads mail to one device
SMTP	mail.yourdomain.com	465	SSL/TLS	Or port 587 with STARTTLS
SMTP	mail.yourdomain.com	587	STARTTLS	Alternative to 465

If You See Certificate Warnings or “Unsecure Connection” Errors

Switch both incoming and outgoing servers to your server’s secure hostname:
secure##.inmotionhosting.com
(Replace ## with your specific server number. You can find this in cPanel under Server Information or by contacting support.)

Authentication

• Select “My outgoing server (SMTP) requires authentication”
• Use the same username and password as your incoming mail
• Disable “Secure Password Authentication (SPA)” if offered

Tip: InMotion provides an Email Configuration Tool that generates exact settings for your domain.

Client Configuration Errors

These errors usually appear when first setting up an email account or after password changes.

Authentication Failed / Login Errors (Incorrect Password or Invalid Username)

Common Messages:

• Authentication failed
• Login incorrect
• Invalid username or password
• 535 Authentication failed (or similar)

Causes:

• Using the wrong password (email account password vs. cPanel password).
• Using only the username instead of the full email address.
• Password recently changed in cPanel but not updated in the email client.
• Outgoing server authentication not enabled.

How to Fix:

1. Log into cPanel → Email Accounts.
2. Locate the email account and reset the password if you’re unsure (use a strong password).
3. In your email client:
   • Update the username field to your full email address ([email protected]).
   • Re-enter the email account password (not cPanel password).
   • Ensure “My outgoing server (SMTP) requires authentication” is checked.
   • Save settings and test sending/receiving.
4. If using multiple devices, update credentials on all of them.

Note: You must use the email account password created or reset in cPanel’s Email Accounts section. The cPanel login password will not work for email.

Unsecure Connection or SSL Certificate Errors / Warnings

Common Messages:

• Unsecure Connection
• Certificate name mismatch
• The server’s certificate does not match the domain
• Warning about self-signed or invalid certificate

Causes:

• Email client is configured to use SSL/TLS but the server hostname (mail.yourdomain.com) triggers a domain mismatch warning on shared hosting.
• Outdated email client or missing root certificates.

How to Fix:

1. In your email client settings, change both the incoming (IMAP/POP) and outgoing (SMTP) server names from mail.yourdomain.com to your server’s secure hostname:
   secure##.inmotionhosting.com
2. Keep SSL/TLS enabled on the recommended ports (993 IMAP, 995 POP, 465/587 SMTP).
3. Accept or trust the certificate if prompted (it is valid for InMotion’s shared infrastructure).
4. Test the connection again.

This resolves the vast majority of SSL-related warnings on InMotion’s hosting plans.

503 Valid RCPT Command Must Precede DATA

Cause:

Your email client is attempting to send a message without properly authenticating to the outgoing SMTP server first.

How to Fix:

1. In your email client’s outgoing server (SMTP) settings:
   • Check the box for “My outgoing server (SMTP) requires authentication”.
   • Select “Use same settings as my incoming mail server” (or manually enter the same username/password).
2. Save and restart the email client.
3. Try sending a test email.

This is a very common issue when first configuring Outlook, Thunderbird, or similar clients.

Other Client-Side Issues

If you continue to see errors after the above steps:

• Double-check that the email account exists in cPanel → Email Accounts.
• Verify your domain’s MX records point to InMotion (especially after transfers or DNS changes).
• Update your email client to the latest version.
• Temporarily disable any VPN, firewall, or antivirus email scanning features.
• Try setting up the account on a different device or client to isolate the issue.

Still stuck with client setup? Submit a support ticket through AMP with screenshots of your client settings and the exact error.

Prevention and Best Practices for InMotion Hosting Customers

• Use SSL/TLS everywhere: Protects credentials and reduces “unsecure” warnings.
• Keep credentials updated: Change email passwords in cPanel and immediately update all clients/apps.
• Monitor your sending reputation: Avoid high-volume sending without proper warm-up or authentication (SPF, DKIM, DMARC recommended for business domains).
• Regularly check cPanel Email Accounts for quota usage and active accounts.
• For VPS/Dedicated users: Implement Fail2Ban or firewall rules to protect against brute-force attacks on port 25/587/465.
• Test thoroughly after any DNS, MX, or account changes.

When to Contact InMotion Hosting Support

Contact our technical support team if:

• You have followed all steps above and the error persists.
• You see repeated bounce codes affecting important business email.
• You need help interpreting server mail logs (VPS/Dedicated).
• You recently migrated email or changed DNS/MX records.

How to Get Help:

• Log into AMP → Submit a Support Ticket (include full error text or bounce message + screenshots).
• Call 757-416-6575 x2 (Current Customers)
• Use Live Chat or the support portal for faster response on urgent issues.

Our team has deep expertise with Exim, cPanel, Control Web Panel, and InMotion infrastructure and can review logs, adjust settings, or escalate delivery issues with recipient providers when appropriate.