无法以编程方式连接到Exchange 2019

Question

我的代码可以很好地连接到Exchange 2017，但是升级到2019后，它就停止了工作。

例外是：

<Trace Tag="AutodiscoverConfiguration" Tid="1" Time="2020-04-25 00:48:18Z">
Trying to call Autodiscover for [email protected] on https://subdomain.mydomain.com/autodiscover/autodiscover.xml.
</Trace>
<Trace Tag="AutodiscoverConfiguration" Tid="1" Time="2020-04-25 00:48:19Z">
 failed: WebException (The underlying connection was closed: An unexpected error occurred on a send.)
</Trace>

如您所见，我已启用跟踪。证书很好，我可以从浏览器连接到https://subdomain.mydomain.com/autodiscover/autodiscover.xml。

有什么问题吗？

这里是代码：

Dim service As New ExchangeService(ExchangeVersion.Exchange2013_SP1)

service.TraceListener = New TraceListener()
service.TraceEnabled = True
service.Credentials = New WebCredentials(Username, Password)
service.AutodiscoverUrl(EmailAddress, AddressOf RedirectionCallback)

Answer 1

[最可能的原因是TLS 1.2，因为Exchange 2019仅接受TLS 1.2连接，我建议您从github https://github.com/OfficeDev/ews-managed-api编译EWS托管API的最新版本，在使用支持的.net框架上检查版本https://docs.microsoft.com/en-us/dotnet/framework/network-programming/tls，也可以显式设置TLS版本

System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;