MX Messaging Resources

I see this warning on my mxtoolbox dashboard.  what does it mean? Does it have anything to do ith my email delays? 

Transaction Time

5.266 seconds - Warning

Thank you for using our Free Diagnostic Tool at http://mxtoolbox.com. 5.266 is not something major to worry about but can be a little concerning. This is the average amount of time it takes for your server to respond when we tried to send a test message. In the world of the Internet this is quite a long amount of time, we like to see transaction times under a second or more.

Thank you,
Wendy