Email remains one of the most critical communication tools for businesses, professionals, and organizations. When sending or receiving emails in webmail fails, it can disrupt operations, cause missed opportunities, and damage professional credibility.
This knowledge-base article provides a complete technical and user-friendly guide to identifying, troubleshooting, and resolving webmail sending and receiving issues. It is designed for:
- Hosting customers
- IT administrators
- Support engineers
- Business users
- Email administrators
By the end of this guide, you will understand why webmail email problems occur, how to diagnose them step by step, and how to prevent them in the future.
2. Understanding How Webmail Works
Webmail is an online interface that allows users to send and receive emails through a browser without configuring a local email client.
Key Components of Webmail Email Delivery
- Mail Server – Handles sending and receiving messages
- SMTP – Used to send emails
- POP3 / IMAP – Used to retrieve emails
- DNS Records – Control routing and authentication
- Spam Filters – Protect inboxes from unwanted messages
If any one of these components fails or is misconfigured, email delivery issues occur.
3. Common Symptoms of Webmail Email Issues
Users may experience one or more of the following problems:
- Emails not sending from webmail
- Emails stuck in Outbox
- Emails not receiving in Inbox
- Missing emails
- Emails going to Spam folder
- Delivery failed error messages
- SMTP authentication errors
- Delayed email delivery
- Login works but email does not function
Understanding the symptom helps narrow down the cause quickly.
4. Major Causes of Sending & Receiving Problems
Most webmail email issues occur due to:
- Full mailbox storage
- Incorrect SMTP settings
- Incorrect MX records
- Spam filtering
- Missing DNS authentication records
- Attachment size limits
- Server IP blacklisting
- Temporary mail server outages
- Account suspension or abuse detection
5. Webmail Not Sending Emails – Detailed Troubleshooting
Common Error Messages
- “Message delivery failed”
- “SMTP authentication error”
- “Connection timed out”
- “Relay access denied”
Possible Causes
- SMTP authentication disabled
- Incorrect outgoing mail server
- Attachment size exceeded
- Server restrictions
- Account quota reached
Resolution Steps
Step 1: Send a Test Email
Send a plain text email without attachments.
- If successful → attachment issue
- If failed → continue troubleshooting
Step 2: Check SMTP Settings
Ensure:
- SMTP authentication is enabled
- Correct port is used (587 or 465)
- SSL/TLS is enabled
- Username is full email address
Step 3: Check Mailbox Quota
A full mailbox can block outgoing messages.
6. Webmail Not Receiving Emails – Detailed Troubleshooting
Possible Causes
- Inbox storage full
- Incorrect MX records
- Spam filtering
- Sender rejection
- Domain DNS issues
Resolution Steps
Step 1: Check Spam Folder
Many emails are filtered automatically.
Step 2: Verify MX Records
MX records must point to the active mail server.
Step 3: Ask Sender for Bounce Message
Bounce messages explain why delivery failed.
7. Emails Going to Spam or Junk Folder
Why Emails Go to Spam
- Missing SPF, DKIM, DMARC
- Poor sender reputation
- Spam-trigger words
- Blacklisted IP
How to Fix Spam Issues
- Configure SPF, DKIM, DMARC
- Avoid spam-like content
- Use proper email formatting
- Maintain good sending practices
8. Delayed or Missing Emails
Causes
- Greylisting
- Server queue backlog
- Temporary DNS issues
- Network delays
Solution
Delayed emails usually resolve automatically, but repeated delays require server investigation.
9. SMTP Errors Explained (Common Error Codes)
| Error Code | Meaning |
|---|---|
| 550 | Mailbox unavailable |
| 553 | Authentication required |
| 554 | Message rejected |
| 421 | Service unavailable |
| 451 | Temporary server error |
Understanding these codes helps diagnose issues faster.
10. DNS & Email Records Explained
MX Records
Define where incoming mail is delivered.
SPF Records
Authorize servers allowed to send emails.
DKIM Records
Add cryptographic signatures to emails.
DMARC Records
Control how receiving servers handle unauthenticated mail.
Incorrect DNS records are a leading cause of email delivery failure.
11. Attachment-Related Email Issues
Common Problems
- File too large
- Blocked file type
- Slow upload
Best Practices
- Keep attachments under 20–25 MB
- Compress files
- Use cloud sharing links
12. Mailbox Storage & Quota Problems
Symptoms
- Emails bounce
- Sending blocked
- Receiving disabled
Solution
- Delete old emails
- Empty Trash and Spam folders
- Upgrade mailbox quota if needed
13. Webmail Login Works but Emails Fail
This usually indicates:
- Mail service issue
- Account restriction
- Corrupted mailbox
Contact hosting support if this occurs.
14. Blacklisting & IP Reputation Issues
What Is Blacklisting?
Mail server IPs listed on spam databases are blocked by receiving servers.
Effects
- Emails rejected
- Emails go to spam
Resolution
- Request delisting
- Improve sending reputation
15. Server-Side Email Problems
Sometimes the issue is not user-related.
Examples:
- Mail queue overload
- Server maintenance
- Hardware failure
These require hosting provider intervention.
16. Email Security & Abuse-Related Blocks
Hosting providers may block email services due to:
- Malware detection
- Spam activity
- Compromised accounts
Always scan devices and reset passwords.
17. Step-by-Step Universal Troubleshooting Checklist
- Check mailbox storage
- Send test email without attachment
- Verify SMTP settings
- Check Spam folder
- Confirm MX records
- Review email logs
- Check SPF, DKIM, DMARC
- Verify blacklist status
- Contact hosting support
18. Best Practices to Prevent Webmail Email Issues
- Keep mailbox usage below 80%
- Use strong passwords
- Enable email authentication
- Monitor email activity
- Avoid mass unsolicited emails
19. When to Contact Hosting Support
Contact support if:
- Errors persist
- DNS changes are required
- Server-side problems suspected
Provide:
- Email address
- Error message
- Date and time
- Recipient details
20. Frequently Asked Questions (FAQs)
Why is webmail not sending emails?
Incorrect SMTP settings, full mailbox, or server issues are common reasons.
Why am I not receiving emails?
Incorrect MX records, spam filtering, or full inbox are typical causes.
How do I stop emails from going to spam?
Configure SPF, DKIM, and DMARC and avoid spam-like content.
What should I do if emails are delayed?
Check server status and logs or contact hosting support.
21. Final Summary & Recommendations
Webmail sending and receiving issues are common but rarely permanent. Most problems can be resolved by checking storage, configuration, and DNS records.
By following this knowledge-base guide, users and administrators can quickly identify issues, apply solutions, and maintain reliable email communication.
For unresolved problems, professional hosting support remains the fastest path to resolution.