It is possible that a poor transaction time could be caused by either a slow down on our system or the specific way that our tool is coded.
The bottom line is that unless you have a poorly configured server or are being victim of a DDOS or Directory Harvest attack, then you shouldn't ever get into the dangerous territory as far as response time goes. Even if under attack a good mail server will go into resource conservation mode and start issuing 400's to defend itself once it's inbound queues are saturated.
Thank you,
Wendy
Wendy
MXToolBox Support
support@mxtoolbox.com