| Class Summary | 
| RelayPath | A class used to represent forward and reverse relay paths. | 
| SimpleSMTPHeader | This class is used to construct a bare minimum
 acceptable header for an email message. | 
| SMTP | SMTP provides the basic the functionality necessary to implement your
 own SMTP client. | 
| SMTPClient | SMTPClient encapsulates all the functionality necessary to send files
 through an SMTP server. | 
| SMTPCommand | SMTPCommand stores a set of constants for SMTP command codes. | 
| SMTPReply | SMTPReply stores a set of constants for SMTP reply codes. |