Hi BGI_Administrator,
We are fully aware of this problem. After investigating , we found the problem is related the Encrypted digits. In IIS6, it only supports 128bit TLS encryption. But in “smtp.office365.com” side , it uses 256bit TLS encryption. It is the reason why connection stop working after establishing. Windows 2008/R2 or later doesn’t have this problem , so use these kind of system as the solution for this case.
Currently ,no workaround or other way for this case with Windows2003. Please understand that to use 256 bit TLS encryption is more secure for your data transmission. Thanks for your understanding.
Regards,
Johnny Zhang