Troubleshooting SMTP/IMAP Connection Issues

If you are experiencing issues with your connected mailbox in our application, it may be due to problems with your SMTP/IMAP server. Our system maintains a continuous connection with your server to track replies, opens, clicks, bounces, and other email activities.

If the connection is lost, our system attempts to reconnect for up to one hour. If all attempts fail, your mailbox will be disconnected.

If you are facing connectivity issues, please check the following potential causes and troubleshooting steps on your end.

1. Verify Your SMTP/IMAP Credentials

Ensure that you have entered the correct email address, username, and password.
If you have recently changed your email password, update it in our application.
Some SMTP/IMAP servers require an application-specific password instead of your usual password for third-party access. Check your server settings.
Be aware of potential typos or extra spaces when copying and pasting credentials.
If using Active Directory authentication, verify that your account has the necessary permissions for IMAP/SMTP access.

2. Check Your SMTP/IMAP Server Settings

Ensure that your SMTP and IMAP servers are configured correctly:

IMAP: Typically port 993 (SSL) or 143 (STARTTLS)
SMTP: Typically port 465 (SSL) or 587 (STARTTLS)
Ensure that SSL/TLS encryption is enabled if required by your server.
Check for any recent configuration changes in your server logs that might be blocking connections.
If your server requires specific authentication methods (e.g., NTLM, Kerberos), make sure they are supported by our application.

3. Allow Access for Third-Party Applications

If your SMTP/IMAP server has security settings that block external applications, ensure that our application is whitelisted.
Check if your mail server requires explicit approval for external connections and manually allow our application.
Ensure that any rate limits or authentication policies applied to external applications are not preventing connections.

4. Ensure IMAP is Enabled

Some custom mail servers disable IMAP by default. Verify that IMAP access is enabled in your server settings.
If using an Exchange server, ensure that IMAP is enabled and properly configured for external access.
Check if there are IMAP restrictions on specific user accounts and modify permissions if necessary.

5. Verify Firewall & Security Software

If your SMTP/IMAP server is hosted internally, ensure that your firewall is not blocking external connections.
Open the necessary ports (IMAP and SMTP) in your firewall settings.
If using an IDS/IPS (Intrusion Detection/Prevention System), check if it is flagging IMAP/SMTP connections and allowlist our application's IP addresses.
Some VPN configurations may interfere with email connections. If applicable, try disabling the VPN and reconnecting.

6. Check for IP Blocking or Rate Limits

If there are too many failed authentication attempts, your server might temporarily block further connections. Check your security logs for blocked IP addresses.
Some SMTP servers impose sending limits to prevent spam:
- Check if your server has daily/hourly limits on outgoing emails and adjust them if possible.
- Some configurations limit the number of concurrent SMTP sessions. Try reducing simultaneous connections.
- If your SMTP server enforces a sending quota, consider distributing email sending over a longer period.
For IMAP, verify that there are no session limits that may cause disconnections.
If using an Exchange server, ensure that the Message Rate Limits and Client Throttling Policies are configured to allow the required email flow.

7. Test Your Connection Independently

You can verify the connectivity by testing SMTP/IMAP manually:

IMAP: Use a third-party email client (e.g., Outlook, Thunderbird) to see if IMAP is working.
SMTP: Use command-line tools to test connectivity:

For IMAP:
```
telnet your-imap-server.com 993
```
For SMTP:
```
telnet your-smtp-server.com 587
```

If telnet is not available, use nc (netcat):

IMAP:

nc -zv your-imap-server.com 993

SMTP:

nc -zv your-smtp-server.com 587

If the connection fails, check your server logs for errors and adjust settings accordingly.

Test authentication with OpenSSL:

IMAP:

openssl s_client -connect your-imap-server.com:993 -crlf

SMTP:

openssl s_client -starttls smtp -connect your-smtp-server.com:587

If successful, you should see a 220 response from the server.

Check DNS records:

nslookup your-smtp-server.com dig your-smtp-server.com MX

Verify connectivity with traceroute:

traceroute your-smtp-server.com traceroute your-imap-server.com

Monitor active connections:

netstat -an | grep :993 # for IMAP netstat -an | grep :587 # for SMTP

8. Check Mail Server Status

If your SMTP/IMAP server is self-hosted, ensure that the service is running without errors.
Review your mail server logs for any failed authentication attempts or connection timeouts.
Check logs in /var/log/mail.log (Linux) or Event Viewer > Applications and Services Logs > Microsoft > Exchange (Windows Exchange Servers).
If using a cloud-hosted mail server, check its status dashboard for outages or maintenance notifications.

Restart the mail services:

Postfix:

systemctl restart postfix

Dovecot:

systemctl restart dovecot

Exchange:

Restart-Service MSExchangeTransport

Check status:

systemctl status postfix

systemctl status dovecot

Need Further Assistance?

If you have checked all the above steps and are still experiencing issues, please contact our support team with the following details:

The SMTP/IMAP server software you are using (e.g., Postfix, Exim, Microsoft Exchange, Zimbra)
The exact error message (if any)
A screenshot of your SMTP/IMAP settings in our application
Any relevant server logs that indicate connection failures

By following these troubleshooting steps, you should be able to restore your SMTP/IMAP connection and continue using email features seamlessly within our application. If you require further help, don't hesitate to reach out!