| | Class | Description |
 | Attachments | Contains all recursive attachments contained in the message. |
 | AttachmentStream | Represents a non-MIME attached file. |
 | AttachmentStreams | A collection of AttachmentStream objects. Inherited from ArrayList. |
 | BusyException | Thrown whenever a method is called to perform an operation when an operation is already in progress. |
 | Certificate | Represents a digital certificate. |
 | CertificateReceivedEventArgs | Provides data for any event where certificates are received. |
 | CertificateStore | Use the CertificateStore Object to gain access to a store of certificates on the local system. |
 | CodingStream | Used to read/write encoded information. |
 | DeliveryStatusNotification | The DeliveryStatusNotification class provides an easy way to handle Delivery Status Notification (DSN) when sending mail using SMTP. |
 | EndEventArgs | Provides data for asynchronous completion events. |
 | EnhancedStream | Adds new methods on top of the Stream interface for type conversion, stream copying, and saving. |
 | ExceptionEventArgs | Provides data for asynchronous event handlers. |
 | Imap | The Imap component enables the integration of Internet Message Access Protocol (IMAP) functionality into any .NET application. |
 | ImapMessage | Represents an IMAP message on the server. |
 | ImapMessageCollection | Contains ImapMessage objects. |
 | ImapMessageEventArgs | Provides data for the Imap events: Imap.EndGetMessage, Imap.EndMessageAdd, Imap.EndSearch. |
 | ImapProgressEventArgs | Provides data for the Imap.Progress event. |
 | ImapResponse | Represents a single line response from an IMAP server. |
 | ImapResponseEventArgs | Provides data for the Imap events: Imap.Alert, Imap.EndClear, Imap.EndCopy, Imap.EndExamine, Imap.EndInvoke, Imap.EndLogin, Imap.EndLogout, Imap.EndMailboxRemove, Imap.EndNoop, Imap.EndPurge, Imap.EndRefresh, Imap.EndSet, Imap.EndSubscribe, Imap.EndSubscribe, Imap.LineReceived, Imap.Update. |
 | ImapSearchParameter | Represents a search parameter used with the MailBox.Search method. |
 | ImapUTF7Encoding | Represents a modified UTF-7 encoding of Unicode characters to be used for IMAP mailbox names. |
 | InvalidParameterTypeException | Thrown whenever a method is called with an invalid parameter. |
 | Invoke | Presents the results from an Internet protocol Request/Response pair. |
 | InvokeEventArgs | This class is passed into EndInvoke events and provides data for these event. |
 | MailAddress | The MailAddress object represents a single email address. |
 | MailAddresses | A collection of MailAddress objects. |
 | Mailbox | Represents an IMAP mailbox on the server. |
 | MailboxCollection | Represents a collection of Mailbox objects. |
 | MailboxEventArgs | Provides data for the Imap.EndMailboxAdd, Imap.EndList, and Imap.Mailbox events. |
 | MailHeader | Collection representing the header of an Internet email message. |
 | MessageBase | Abstract base class for all server-side mail messages. |
 | MessagePartEventArgs | Provides data for the Imap.EndGetPart event. |
 | MessagePartStream | Represents a simple inline MIME part. |
 | MessagePartStreams | A collection of MessagePartStream objects. Inherited from ArrayList. |
 | MessageStream | Represents an email message. |
 | MessageStreams | A collection of MessageStream objects. Inherited from ArrayList. |
 | MimeAttachmentStream | Represents a MIME attachment. |
 | MimeAttachmentStreams | A collection of MimeAttachmentStream objects. Inherited from ArrayList. |
 | NonMime | Contains all non-MIME parts of a message. |
 | PartList | Used as the base class for MessagePartStreams, MessageStreams, and MimeAttachmentStreams. |
 | Parts | The Parts class contains collections of MIME part collections. |
 | PipeStream | Represents a stream that wraps an internal stream. |
 | Pop | The Pop component enables the integration of Post Office Protocol (POP) functionality into any .NET application. |
 | PopEventArgs | This class is passed into the Pop.EndGet event and provides data for this event. |
 | PopMessage | Represents a message on a POP server. |
 | PopProgressEventArgs | This class is passed into the Pop.Progress event and provides data for this event. |
 | ProgressEventArgs | This class is passed into the Progress event and provides data for this event. |
 | ProtocolException | Used to throw protocol exceptions for upper-layer protocols like FTP, SMTP and POP3. |
 | Proxy | Provides an easy way to manage communication with proxy servers |
 | Response | Presents the response portion from an Internet protocol Request/Response pair. |
 | Segment | Provides a reference to a data segment where data is sent or received over a TCP stream. |
 | SegmentedStream | Used to provide advanced reading/writing capabilities to Stream-based objects. |
 | SegmentEventArgs | Provides data for any event where data is sent or received. |
 | SimpleCollectionBase | Collection class that provides basic functionality for the server-side collections. |
 | Smtp | The Smtp component enables easy integration of Simple Mail Transport Protocol (SMTP) functionality within any .NET application. |
 | SmtpEventArgs | This class is passed into the Smtp.EndSend event and provides data for this event. |
 | SmtpResult | Represents the results from an SMTP send operation. |
 | Tcp | The Tcp component provides comprehensive Transmission Control Protocol support. |
 | TcpStream | TcpStream implements sending and receiving of data through network sockets. |