Here’s a link to a useful web based MX record lookup tool. As well as giving you the MX record details for a particular domain you can also use the ‘Diagnostics’ section to:
- Check connectivity to the mail server
- Verify Reverse DNS records
- Perform a simple Open Relay check
- Measure response time performance
- Check against 147 DNS based blacklists
It’s a useful tool to have when trying to resolve any email based connectivity/delivery problems. Also, check out Ted’s Tools – this site includes a number of useful online lookup tools.