TIdSMTPState is an enumerated type that represents the various stages in an SMTP client conversation that have been successfully completed. TIdSMTPState may contain on of the following values and associated meanings:
idSMTPNone - No SMTP operations have been performed.
idSMTPHelo - Client has been identified using the SMTP command HELO or EHLO.
idSMTPMail - Client has successfully performed the SMTP MAIL command.
idSMTPRcpt - Client has sent the recipient data for the mail message.
idSMTPData - Client has sent the mail data for the message.