SecurityProtocol Enumeration
Specifies the protocols to be used for performing TLS/SSL negotiation and data encryption.

Namespace: MailBee.Security
Assembly: MailBee.NET (in MailBee.NET.dll) Version: 11.2.0 build 590 for .NET 4.5
Syntax
[FlagsAttribute]
public enum SecurityProtocol
Members
  Member nameValueDescription
Auto0The most secure protocol supported by the server will be used to authenticate the client and encrypt the data as specified by SecurityProtocol setting (if it's available and set). If it's not, TlsAuto will be tried. For better security, select TLS 1.2 explicitly (provided that the server supports TLS 1.2 as well) or TlsAuto at least.
Ssl212SSL 2.0 will be used to authenticate the client and encrypt the data. Highly vulnerable!
Ssl348SSL 3.0 will be used to authenticate the client and encrypt the data. Highly vulnerable!
Tls1192TLS 1.0 will be used to authenticate the client and encrypt the data. Somewhat vulnerable but still the best option for .NET 4.0 and earlier.
Tls11768TLS 1.1 will be used to authenticate the client and encrypt the data.
Tls123072TLS 1.2 will be used to authenticate the client and encrypt the data. The highest level of security.
TlsAuto4032 TLS 1.2 will be used if supported by the server. If not, falls back to TLS 1.1 and if it's not supported either, falls back to TLS 1.0. Highly vulnerable SSL 3.0 and its predecessors will NOT be tried anyway. This option is a decent trade-off between security and compatibility.
Remarks

The security protocol can be set via SslProtocol property of SmtpServer, Pop3, or Imap classes.

If the mail server does not support automatic protocol negotiation (this usually results in getting MailBeeSocketResetException thrown during TLS/SSL negotiation), the developer should mannually specify the protocol to be used (for example Tls1).

Note Note
In case of UWP platform, MailBee always uses TlsAuto setting.
See Also