When you experience the subject behavior, you may receive a 10060 connection timed out error message.

The following message services may be affected:

Simple Mail Transfer Protocol (SMTP)
Message Transfer Agent (MTA)
Winmgmt

This behavior will occur if the subnet mask on the host computer is 255.255.255.255, causing the source address to be invalid when a loop back packet is processed on the receive side.

To workaround this problem, use a valid subnet mask.