How to resolve a 'connection refused' network error when sending emails?

Email marketer from SiteGround explains checking the server's status page to see if there are any known issues affecting mail services. If there are no known issues, contact their support team for further assistance.

Email marketer from MXToolbox explains using their tools to check for DNS issues and blacklist status. Incorrect DNS settings can prevent your mail server from finding the recipient's server, and being on a blacklist will cause connections to be refused.

Marketer from Email Geeks suggests contacting someone at synaq.com and offers to organize a tracert.

Email marketer from StackOverflow recommends first checking if the service is running on the target machine and listening on the expected port. They advise using tools like `netstat` or `ss` to verify this. Next, they suggest checking firewall settings that might be blocking the connection. Finally, they propose testing connectivity with `telnet` or `nc` to isolate the issue.

Email marketer from Email on Acid shares using telnet to test your SMTP connection. If you can't connect with telnet, the problem likely lies with your network or firewall.

Email marketer from SuperUser forum says that a common reason is the mail server being overloaded or temporarily unavailable. They recommend trying again later. Also, ensure your sending IP address isn't blacklisted by the receiving mail server.

Email marketer from cPanel forums recommends carefully configuring the firewall to allow outgoing connections on the necessary SMTP ports (25, 465, 587). Also, ensure that the firewall isn't blocking incoming connections to your own mail server.

Email marketer from DigitalOcean shares making sure that your mail server software (e.g., Postfix, Sendmail) is properly configured and listening on the correct port. It also means checking your server's resource usage (CPU, memory) to ensure it's not overloaded.

Email marketer from Reddit shares that common causes include the service not running, a firewall blocking the connection, or incorrect DNS resolution. Suggests verifying that the mail server is running, that the firewall allows connections on port 25, 465, or 587, and that the domain name resolves to the correct IP address.

Expert from Spam Resource explains to check the SMTP banner for clues. The banner is what the receiving server says when you first connect to it. Sometimes, it will give a specific reason for refusing the connection, such as 'too many connections' or 'blacklisted IP'.

Expert from Word to the Wise explains greylisting, where the receiving server temporarily refuses the connection from an unknown sender. This is done to block spammers who don't retry sending. A legitimate server should retry after a delay. Therefore, retrying the email after a short period is the solution.

Expert from Email Geeks explains that the error is a network error, meaning the sender's server cannot connect to the receiving server. It can't reach it due to a routing table issue. Suggests checking connectivity manually on port 25 and running a traceroute to the IP address to determine if it's a routing failure or a deliberate block. Mentions that they seem to be using synaq.com as their MX gateway.

Documentation from Postfix.org explains checking the Postfix logs for clues about the connection failure. It suggests looking for error messages that indicate why the connection was refused, such as authentication failures, policy restrictions, or resource limits.

Documentation from Exim.org explains using Exim's debugging options to trace the connection attempt and identify where the connection is being refused. This often involves using the `-d` flag with increasing levels of verbosity to see the SMTP conversation.

Documentation from Nmap.org explains the using nmap can help diagnose network connectivity. It suggests using Nmap to scan the target host and port to check if the port is open, filtered, or closed. A 'closed' port often indicates that the connection is being refused. Firewalls or service unavailability can be the cause.

Documentation from Sendmail.org explains using `sendmail -v` to run Sendmail in verbose mode. This will provide more detailed output about the connection process, including any errors encountered.

Documentation from Microsoft Learn explains that a 'connection refused' error indicates that the target host is actively refusing the connection attempt. It suggests verifying the destination IP address and port, ensuring the target service is running and listening on the specified port, and checking firewall rules on both the client and server to allow the connection.