property AuthType: TSmtpAuthType;
Inherited from TCustomSmtpCli.AuthType
Property AuthType specifies the authentication method to be used with method Auth. Authentication is necessary to login in the mail server as you're otherwise not allowed to send any e-mails. Most internet service providers require some sort of authentication. The list of possible values below contains such methods like username password without sophisticated encryption or checksum or stronger methods which use MD5 or Sha1 hash algorithms.
Possible values are:
smtpAuthNone, smtpAuthPlain, smtpAuthLogin, smtpAuthCramMD5, smtpAuthCramSha1, smtpAuthAutoSelect
Most of them are self-explaining. With AuthType smtpAuthAutoSelect the component performs a smart detection of most secure authentication method possible, however it won't fall back to smtpAuthNone.
SmtpCli1.AuthType := smtpAuthAutoSelect;
Recommended setting is smtpAuthAutoSelect.