Trouble shooting tools:
1. Ensure that mx records of the domain are pointing to our servers, this can be done by doing a dnslookup via: intodns.com. Look for the mx records of the domain and ensure it is resolving to our IP.
2. Always check the mail server health via mxtoolbox.com. This will give you all the information regarding the mail servers response time, ptr and any black lists that the domain or mail server might be on.
Methods for troubleshooting incoming mail:
1. Mail cannot be received by client: Always test webmail to check if the issue is on the server side or within the clients network, where mail is being received by the server and not the clients network.
2. If mail is on the server but not going through to the client, ensure that their incoming server settings are correct, they should read as below:
Incoming: mail.domainname Port: 110. The username needs to be the full email address of the client where ever the confgiration asks for a username.
3. Ensure that the client is working online within their mail program.
4. Check the mailbox qouta.
5. If there is a port issue where a port is being blokced, do a telnet to the incoming ports from the clients machine to see if something on their end is blocking the incoming port, if not blocked you will get 250OK if not you will receive an error. If the port is indeed blocked, try disabling the anti-virus and if we are not the ISP, ask the client to check with their ISP if any ports are being blocked.
Methods for troubleshooting outgoing mail:
1. Mail cannot be sent out by client: Same as the incoming, always test from webmail to see if the issue is on the server end or the clients end.
2. Ensure that the outgoing mail server is : mail.domainname or smtp.domainname or they can use the smtp of their ISP.
3. Ensure that both the clients public IP and that our server IP is not on any black list, this can affect outgoing mail.
4. Ensure that smtp authentication is enabled and outgoing port 587 is in use (tsl)
5. If there is a port issue where a port is being blokced, do a telnet to the incoming ports from the clients machine to see if something on their end is blocking the incoming port, if not blocked you will get 250OK if not you will receive an error. If the port is indeed blocked, try disabling the anti-virus and if we are not the ISP, ask the client to check with their ISP if any ports are being blocked.
NB: If for some reason there are multiple mx records, ensure that the priority settings are correct and if they are not using us for mail but we are hosting the domain, ensure that in WHM the domain is configured to "remote mail exhange"
General: If the domain is on our NS but the mail is pointing elsewhere, ensure that the records are correct and live, if our NS is reachable but the mx record is not reachable the issue is not on our end, just as if a domain is not on our NS but we are hosting the mail, ensure that our record is reachable. If a client is receiving huge amounts of span, check the mail logs of the domain, this can be done via ssh and the command to be run is : grep "emailaddress or username of domain" /var/log/exim_mainlog. This will pull up all logs, showing you all incoming and outgoing mails along with the subject line, the sending IP as well as the sending domain and host. By Checking the IPs we can trace where the spam is coming from and block it, we can also see if a user is compromised based on authentication faluire patterns in the logs. You can also trace mails if you log into webmail and check the mail headers.
