Methods of Authentication for Mail Servers

The following table describes the different methods of mail server authentication that can be selected for incoming and outgoing email on the Email Settings window.

Authentication Method	Description
(No authentication)	No authentication is used. This is often used with SMTP servers.
Standard Authentication	The Standard authentication method is used. Passwords are transmitted as clear-text. This method is not supported by SMTP servers.
APOP Authentication	Secure APOP authentication. This is supported by most POP3 servers, but cannot be used with other servers like SMTP because APOP is not a SASL method.
SASL Login Authentication	SASL LOGIN authentication. It is not secure but is widely supported. Passwords are transmitted as Base64 strings.
SASL Plain Authentication	SASL PLAIN authentication. It is not secure but is widely supported. Passwords are transmitted as Base64 strings.
SASL Cram-MD5 Authentication	Secure SASL CRAM-MD5 authentication. Might not be supported by particular server implementations.
SASL Digest-MD5 Authentication	Secure SASL DIGEST-MD5 authentication. Might not be supported by particular server implementations.
SASL NTLM Authentication	Secure SASL NTLM authentication (also known as Secure Password Authentication - SPA). Might not be supported by particular server implementations.
SASL MSN Authentication	Secure SASL MSN authentication (equivalent to NTLM). Might not be supported by particular server implementations.
SASL GSS Authentication	Secure SASL GSS API authentication (Kerberos). Used to authenticate the current Windows account in Windows domain environments such as Active Directory.