This chapter summarizes essential information about the Internet Protocols accessed through the Messaging Access SDK.

• Supported SMTP Internet Protocol Commands. SMTP (Simple Mail Transfer Protocol) sends messages.
• Supported IMAP4 Internet Protocol Commands. IMAP4 (Internet Message Access Protocol) retrieves and manages messages remotely.
• Supported POP3 Internet Protocol Commands. POP3 (Post Office Protocol) downloads messages to a client and allows for search and retrieval of messages.
• MIME, Multipurpose Internet Mail Extension. MIME builds code messages with attachments for sending with SMTP, and parses and decodes received messages. SDK MIME methods and functions do not map to a set of Internet Protocol commands in the same way that the other protocols do.

Supported SMTP Internet Protocol Commands

Supported Internet Protocol command	What the command does	SMTPClient method that calls the command
DATA	Informs server that the client is about to send the message. After server OK, client sends RFC 822-compliant message data line by line. On completion, client sends "<CRLF>.<CRLF>" line.	data
DSN [NOTIFY, RET, ENVID]	Allows SMTP client to generate delivery status notifications (DSNs) when needed, determine whether the notifications return the message contents, and get additional information with a DSN so that the sender can identify both recipient(s) for the DSN and the transaction that contained the original message. (RFC 1891)
EHLO	Client starts SMTP session by sending identification to server; server responds (identifies itself) in a greeting message. EHLO replaces older HELO command for SMTP clients that support SMTP service extensions. Can be issued at the start of the session to see which extensions the server supports.	ehlo
EXPN	Expands a mailing list alias; the command retrieves the alias member list.	expand
HELP	Calls the server Help utility. Application-specific; usually lists available commands.	help
MAIL FROM	Initiates sending the message; supplies the message's reverse path (usually the sender's fully qualified domain name).	mailFrom
NOOP	Gets positive server response.	noop
QUIT	Sent by a client to a server when the client is ready to end the session. Server sends response and closes TCP connection. Best to use this command rather than just closing the connection.	quit
PIPELINING	Allows command pipelining (batching multiple commands into single TCP sends). To find out if server supports pipelining, issue the EHLO command. If it does, the server response includes code 250 and EHLO keyword PIPELINING. Pipelining allows the client to transmit batches of SMTP commands without waiting for a response to each. (RFC 2197)
RCPT TO	Specifies the address of a message recipient. Called once for each recipient. Follows the MAIL command.	rcptTo
RSET	Cancels the current mail transfer and all current processes, discards data, and clears session states. Returns to the session state that followed the EHLO command.	reset
VRFY	Sent by a client to verify a user name with the server. The server responds with a positive or negative code.	verify

Supported IMAP4 Internet Protocol Commands

Supported Internet Protocol command	What the command does	Session state for command	IMAP4Client method that calls the command
APPEND	Appends message to specified mailbox, passes on any message flags.	Authenticated	append
CAPABILITY	Gets a list of server capabilities.	All states	capability
CHECK	Requests a checkpoint of the currently selected mailbox; server flushes existing mailbox states to disk.	Selected	check
CLOSE	Closes a mailbox, deletes flagged messages, moves session to Non-Authenticated state.	Selected	close
COPY	Copies a message to the specified mailbox.	Selected	copy
CREATE	Creates a mailbox.	Authenticated	create
DELETE	Marks a message for deletion.	Authenticated	delete
EXAMINE	Like SELECT, but read-only.	Authenticated	examine
EXPUNGE	Removes all messages flagged "\Deleted" in a mailbox.	Selected	expunge
FETCH	Returns information from messages. The protocol's FETCH [XSENDER] form is supported.	Selected	fetch
LIST	Gets list of user names.	Authenticated	list
LOGIN	Logs in to server with user name and password.	Non-Authenticated	login
LOGOUT	Ends session; server responds with "BYE."	All states	logout
LSUB	Lists members of subscription list (must be added with SUBSCRIBE).	Authenticated	lsub
NAMESPACE	Retrieves the prefixes of namespaces used by a server for personal mailboxes, other user's mailboxes, and shared mailboxes.	All states	namespace
NOOP	Gets positive server response.	All states	noop
RENAME	Renames mailbox.	Authenticated	rename
SEARCH	Finds messages that meet specified criteria.	Selected	search
SELECT	Selects a mailbox on the server for operations involving messages.	Authenticated	select
STATUS	Requests one or more types of status for the specified mailbox.	Authenticated	status
STORE	Updates flags on messages; can return the new flag status.	Selected	store
SUBSCRIBE	Adds a mailbox to a server's subscribed mailbox list. List is accessed with LSUB.	Authenticated	subscribe
UID	Used with a command name to specify that it uses unique message identifiers.	Selected	uidCopy uidFetch uidSearch uidStore
UNSUBSCRIBE	Deletes a mailbox from a server's subscribed mailbox list. List is accessed with LSUB.	Authenticated	unsubscribe
SETACL	Changes the access control list on the specified mailbox and grants specified permissions.	All states	setACL
DELETEACL	Removes an <identifier, rights> pair for the specified identifier from the access control list for the specified mailbox.	All states	deleteACL
GETACL	Retrieves the access control list for the mailbox in an untagged ACL reply.	All states	getACL
LISTRIGHTS	Retrieves the access control list for mailbox in an untagged ACL reply.	All states	listRights
MYRIGHTS	Retrieves the user's rights to the specified mailbox.	All states	myRights

Supported POP3 Internet Protocol Commands

Supported Internet Protocol command	What the command does	Session state for command	POP3Client method that calls the command
DELE	Asks server to mark specified message for deletion. Deletion actually takes place on entry into Update state.	Transaction	delete
LIST	Gets the size of one or all messages.	Transaction	list listA
NOOP	Gets positive server response.	Transaction	noop
PASS	Identifies a user password; on success, moves session to the Transaction state.	Authorization	pass
QUIT	Ends the session. If issued in Authentication state, server closes connections. If issued in Transaction state, server goes into Update and deletes any marked messages, then quits.	Authorization, Update	quit
RSET	Asks the server to clear all delete tags from messages.	Transaction	reset
RETR	Requests the entire specified message.	Transaction	retrieve
STAT	Gets the number of messages in and octet size of mail drop.	Transaction	stat
TOP	Asks server for first n lines of specified message.	Transaction	top
UIDL	Gets the unique identifier string for specified or all messages.	Transaction	uidList uidListA
USER	Identifies the user or mail drop by name to the server; the server returns a known or unknown response.	Authorization	user
XAUTHLIST	Returns a list of authenticated users.	Transaction	xAuthList xAuthListA
XSENDER	Gets the email address of the sender of the specified message. Client uses this to query whether an individual message has been authenticated. Server returns an empty OK string if no authenticated sender is found.	Transaction	xSender

Last Updated: June 3, 1998