Net::IMAP

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality. The protocol is described in [IMAP].

IMAP Overview

An IMAP client connects to a server, and then authenticates itself using either authenticate() or login(). Having authenticated itself, there is a range of commands available to it. Most work with mailboxes, which may be arranged in an hierarchical namespace, and each of which contains zero or more messages. How this is implemented on the server is implementation-dependent; on a UNIX server, it will frequently be implemented as a files in mailbox format within a hierarchy of directories.

To work on the messages within a mailbox, the client must first select that mailbox, using either select() or (for read-only access) examine(). Once the client has successfully selected a mailbox, they enter selected state, and that mailbox becomes the current mailbox, on which mail-item related commands implicitly operate.

Messages have two sorts of identifiers: message sequence numbers, and UIDs.

Message sequence numbers number messages within a mail box from 1 up to the number of items in the mail box. If new message arrives during a session, it receives a sequence number equal to the new size of the mail box. If messages are expunged from the mailbox, remaining messages have their sequence numbers “shuffled down” to fill the gaps.

UIDs, on the other hand, are permanently guaranteed not to identify another message within the same mailbox, even if the existing message is deleted. UIDs are required to be assigned in ascending (but not necessarily sequential) order within a mailbox; this means that if a non-IMAP client rearranges the order of mailitems within a mailbox, the UIDs have to be reassigned. An IMAP client cannot thus rearrange message orders.

Examples of Usage

List sender and subject of all recent messages in the default mailbox

imap = Net::IMAP.new('mail.example.com')
imap.authenticate('LOGIN', 'joe_user', 'joes_password')
imap.examine('INBOX')
imap.search(["RECENT"]).each do |message_id|
  envelope = imap.fetch(message_id, "ENVELOPE")[0].attr["ENVELOPE"]
  puts "#{envelope.from[0].name}: \t#{envelope.subject}"
end

Move all messages from April 2003 from “Mail/sent-mail” to “Mail/sent-apr03”

imap = Net::IMAP.new('mail.example.com')
imap.authenticate('LOGIN', 'joe_user', 'joes_password')
imap.select('Mail/sent-mail')
if not imap.list('Mail/', 'sent-apr03')
  imap.create('Mail/sent-apr03')
end
imap.search(["BEFORE", "30-Apr-2003", "SINCE", "1-Apr-2003"]).each do |message_id|
  imap.copy(message_id, "Mail/sent-apr03")
  imap.store(message_id, "+FLAGS", [:Deleted])
end
imap.expunge

Thread Safety

Net::IMAP supports concurrent threads. For example,

imap = Net::IMAP.new("imap.foo.net", "imap2")
imap.authenticate("cram-md5", "bar", "password")
imap.select("inbox")
fetch_thread = Thread.start { imap.fetch(1..-1, "UID") }
search_result = imap.search(["BODY", "hello"])
fetch_result = fetch_thread.value
imap.disconnect

This script invokes the FETCH command and the SEARCH command concurrently.

Errors

An IMAP server can send three different types of responses to indicate failure:

NO: the attempted command could not be successfully completed. For instance, the username/password used for logging in are incorrect; the selected mailbox does not exists; etc.
BAD: the request from the client does not follow the server's understanding of the IMAP protocol. This includes attempting commands from the wrong client state; for instance, attempting to perform a SEARCH command without having SELECTed a current mailbox. It can also signal an internal server failure (such as a disk crash) has occurred.
BYE: the server is saying goodbye. This can be part of a normal logout sequence, and can be used as part of a login sequence to indicate that the server is (for some reason) unwilling to accept our connection. As a response to any other command, it indicates either that the server is shutting down, or that the server is timing out the client connection due to inactivity.

These three error response are represented by the errors Net::IMAP::NoResponseError, Net::IMAP::BadResponseError, and Net::IMAP::ByeResponseError, all of which are subclasses of Net::IMAP::ResponseError. Essentially, all methods that involve sending a request to the server can generate one of these errors. Only the most pertinent instances have been documented below.

Because the IMAP class uses Sockets for communication, its methods are also susceptible to the various errors that can occur when working with sockets. These are generally represented as Errno errors. For instance, any method that involves sending a request to the server and/or receiving a response from it could raise an Errno::EPIPE error if the network connection unexpectedly goes down. See the socket(7), ip(7), tcp(7), socket(2), connect(2), and associated man pages.

Finally, a Net::IMAP::DataFormatError is thrown if low-level data is found to be in an incorrect format (for instance, when converting between UTF-8 and UTF-16), and Net::IMAP::ResponseParseError is thrown if a server response is non-parseable.

References

[IMAP]

Crispin, “INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1”,

RFC 2060, December 1996. (Note: since obsoleted by RFC 3501)

[LANGUAGE-TAGS]

Alvestrand, H., “Tags for the Identification of Languages”, RFC 1766, March 1995.

[MD5]

Myers, J., and M. Rose, “The Content-MD5 Header Field”, RFC 1864, October 1995.

[MIME-IMB]

Freed, N., and N. Borenstein, “MIME (Multipurpose Internet Mail Extensions) Part One: Format of Internet Message Bodies”, RFC 2045, November 1996.

[RFC-822]

Crocker, D., “Standard for the Format of ARPA Internet Text Messages”, STD 11, RFC 822, University of Delaware, August 1982.

[RFC-2087]

Myers, J., “IMAP4 QUOTA extension”, RFC 2087, January 1997.

[RFC-2086]

Myers, J., “IMAP4 ACL extension”, RFC 2086, January 1997.

[RFC-2195]

Klensin, J., Catoe, R., and Krumviede, P., “IMAP/POP AUTHorize Extension for Simple Challenge/Response”, RFC 2195, September 1997.

[SORT-THREAD-EXT]

Crispin, M., “INTERNET MESSAGE ACCESS PROTOCOL - SORT and THREAD Extensions”, draft-ietf-imapext-sort, May 2003.

[OSSL]

www.openssl.org

[RSSL]

savannah.gnu.org/projects/rubypki

[UTF7]

Goldsmith, D. and Davis, M., “UTF-7: A Mail-Safe Transformation Format of Unicode”, RFC 2152, May 1997.

Namespace

Methods

A

add_authenticator,
add_response_handler,
append,
authenticate

C

capability,
check,
close,
copy,
create

D

debug,
debug=,
decode_utf7,
default_imap_port,
default_imaps_port,
default_port,
default_ssl_port,
default_tls_port,
delete,
disconnect,
disconnected?

E

encode_utf7,
examine,
expunge

F

fetch,
format_date,
format_datetime

G

getacl,
getquota,
getquotaroot

I

idle,
idle_done

L

list,
login,
logout,
lsub

M

max_flag_count,
max_flag_count=

N

new,
noop

R

remove_response_handler,
rename

S

search,
select,
setacl,
setquota,
sort,
starttls,
status,
store,
subscribe

T

thread

U

uid_copy,
uid_fetch,
uid_search,
uid_sort,
uid_store,
uid_thread,
unsubscribe

X

xlist

Included Modules

Constants

SEEN	=	:Seen
	Flag indicating a message has been seen
ANSWERED	=	:Answered
	Flag indicating a message has been answered
FLAGGED	=	:Flagged
	Flag indicating a message has been flagged for special or urgent attention
DELETED	=	:Deleted
	Flag indicating a message has been marked for deletion. This will occur when the mailbox is closed or expunged.
DRAFT	=	:Draft
	Flag indicating a message is only a draft or work-in-progress version.
RECENT	=	:Recent
	Flag indicating that the message is “recent”, meaning that this session is the first session in which the client has been notified of this message.
NOINFERIORS	=	:Noinferiors
	Flag indicating that a mailbox context name cannot contain children.
NOSELECT	=	:Noselect
	Flag indicating that a mailbox is not selected.
MARKED	=	:Marked
	Flag indicating that a mailbox has been marked “interesting” by the server; this commonly indicates that the mailbox contains new messages.
UNMARKED	=	:Unmarked
	Flag indicating that the mailbox does not contains new messages.
CRLF	=	"\r\n"

PORT	=	143

SSL_PORT	=	993

DATE_MONTH	=	%w(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec)

ContinuationRequest	=	Struct.new(:data, :raw_data)
	Net::IMAP::ContinuationRequest represents command continuation requests. The command continuation request response is indicated by a “+” token instead of a tag. This form of response indicates that the server is ready to accept the continuation of a command from the client. The remainder of this response is a line of text. `continue_req ::= "+" SPACE (resp_text / base64)` Fields: data Returns the data (Net::IMAP::ResponseText). raw_data Returns the raw data string.
UntaggedResponse	=	Struct.new(:name, :data, :raw_data)
	Net::IMAP::UntaggedResponse represents untagged responses. Data transmitted by the server to the client and status responses that do not indicate command completion are prefixed with the token “”, and are called untagged responses. `response_data ::= "" SPACE (resp_cond_state / resp_cond_bye / mailbox_data / message_data / capability_data)` Fields: name Returns the name such as “FLAGS”, “LIST”, “FETCH”.… data Returns the data such as an array of flag symbols, `a ((<Net::IMAP::MailboxList>)) object....` raw_data Returns the raw data string.
TaggedResponse	=	Struct.new(:tag, :name, :data, :raw_data)
	Net::IMAP::TaggedResponse represents tagged responses. The server completion result response indicates the success or failure of the operation. It is tagged with the same tag as the client command which began the operation. `response_tagged ::= tag SPACE resp_cond_state CRLF tag ::= 1*<any ATOM_CHAR except "+"> resp_cond_state ::= ("OK" / "NO" / "BAD") SPACE resp_text` Fields: tag Returns the tag. name Returns the name. the name is one of “OK”, “NO”, “BAD”. data Returns the data. See ((<Net::IMAP::ResponseText>)). raw_data Returns the raw data string.
ResponseText	=	Struct.new(:code, :text)
	Net::IMAP::ResponseText represents texts of responses. The text may be prefixed by the response code. `resp_text ::= ["[" resp_text_code "]" SPACE] (text_mime2 / text) ;; text SHOULD NOT begin with "[" or "="` Fields: code Returns the response code. See ((<Net::IMAP::ResponseCode>)). text Returns the text.
ResponseCode	=	Struct.new(:name, :data)
	Net::IMAP::ResponseCode represents response codes. `resp_text_code ::= "ALERT" / "PARSE" / "PERMANENTFLAGS" SPACE "(" #(flag / "\") ")" / "READ-ONLY" / "READ-WRITE" / "TRYCREATE" / "UIDVALIDITY" SPACE nz_number / "UNSEEN" SPACE nz_number / atom [SPACE 1<any TEXT_CHAR except "]">]` Fields: name Returns the name such as “ALERT”, “PERMANENTFLAGS”, “UIDVALIDITY”.… data Returns the data if it exists.
MailboxList	=	Struct.new(:attr, :delim, :name)
	Net::IMAP::MailboxList represents contents of the LIST response. `mailbox_list ::= "(" #("\Marked" / "\Noinferiors" / "\Noselect" / "\Unmarked" / flag_extension) ")" SPACE (<"> QUOTED_CHAR <"> / nil) SPACE mailbox` Fields: attr Returns the name attributes. Each name attribute is a symbol capitalized by String#capitalize, such as :Noselect (not :NoSelect). delim Returns the hierarchy delimiter name Returns the mailbox name.
MailboxQuota	=	Struct.new(:mailbox, :usage, :quota)
	Net::IMAP::MailboxQuota represents contents of GETQUOTA response. This object can also be a response to GETQUOTAROOT. In the syntax specification below, the delimiter used with the “#” construct is a single space (SPACE). `quota_list ::= "(" #quota_resource ")" quota_resource ::= atom SPACE number SPACE number quota_response ::= "QUOTA" SPACE astring SPACE quota_list` Fields: mailbox The mailbox with the associated quota. usage Current storage usage of mailbox. quota Quota limit imposed on mailbox.
MailboxQuotaRoot	=	Struct.new(:mailbox, :quotaroots)
	Net::IMAP::MailboxQuotaRoot represents part of the GETQUOTAROOT response. (GETQUOTAROOT can also return Net::IMAP::MailboxQuota.) `quotaroot_response ::= "QUOTAROOT" SPACE astring *(SPACE astring)` Fields: mailbox The mailbox with the associated quota. quotaroots Zero or more quotaroots that effect the quota on the specified mailbox.
MailboxACLItem	=	Struct.new(:user, :rights, :mailbox)
	Net::IMAP::MailboxACLItem represents response from GETACL. `acl_data ::= "ACL" SPACE mailbox *(SPACE identifier SPACE rights) identifier ::= astring rights ::= astring` Fields: user Login name that has certain rights to the mailbox that was specified with the getacl command. rights The access rights the indicated user has to the mailbox.
StatusData	=	Struct.new(:mailbox, :attr)
	Net::IMAP::StatusData represents contents of the STATUS response. Fields: mailbox Returns the mailbox name. attr Returns a hash. Each key is one of “MESSAGES”, “RECENT”, “UIDNEXT”, “UIDVALIDITY”, “UNSEEN”. Each value is a number.
FetchData	=	Struct.new(:seqno, :attr)
	Net::IMAP::FetchData represents contents of the FETCH response. Fields: seqno Returns the message sequence number. (Note: not the unique identifier, even for the UID command response.) attr Returns a hash. Each key is a data item name, and each value is its value. The current data items are: BODY A form of BODYSTRUCTURE without extension data. Net::IMAP::BodyTypeBasic, Net::IMAP::BodyTypeText, Net::IMAP::BodyTypeMessage, Net::IMAP::BodyTypeMultipart. ENVELOPE A Net::IMAP::Envelope object that describes the envelope structure of a message. FLAGS A array of flag symbols that are set for this message. flag symbols are capitalized by String#capitalize. INTERNALDATE A string representing the internal date of the message. RFC822 Equivalent to BODY[]. RFC822.HEADER Equivalent to BODY.PEEK. RFC822.SIZE A number expressing the [RFC-822] size of the message. RFC822.TEXT Equivalent to BODY. UID A number expressing the unique identifier of the message.
Envelope	=	Struct.new(:date, :subject, :from, :sender, :reply_to, :to, :cc, :bcc, :in_reply_to, :message_id)
	Net::IMAP::Envelope represents envelope structures of messages. Fields: date Returns a string that represents the date. subject Returns a string that represents the subject. from Returns an array of Net::IMAP::Address that represents the from. sender Returns an array of Net::IMAP::Address that represents the sender. reply_to Returns an array of Net::IMAP::Address that represents the reply-to. to Returns an array of Net::IMAP::Address that represents the to. cc Returns an array of Net::IMAP::Address that represents the cc. bcc Returns an array of Net::IMAP::Address that represents the bcc. in_reply_to Returns a string that represents the in-reply-to. message_id Returns a string that represents the message-id.
Address	=	Struct.new(:name, :route, :mailbox, :host)
	Net::IMAP::Address represents electronic mail addresses. Fields: name Returns the phrase from [RFC-822] mailbox. route Returns the route from [RFC-822] route-addr. mailbox nil indicates end of [RFC-822] group. If non-nil and host is nil, returns [RFC-822] group name. Otherwise, returns [RFC-822] local-part host nil indicates [RFC-822] group syntax. Otherwise, returns [RFC-822] domain name.
ContentDisposition	=	Struct.new(:dsp_type, :param)
	Net::IMAP::ContentDisposition represents Content-Disposition fields. Fields: dsp_type Returns the disposition type. param Returns a hash that represents parameters of the Content-Disposition field.
ThreadMember	=	Struct.new(:seqno, :children)
	Net::IMAP::ThreadMember represents a thread-node returned by #thread Fields: seqno The sequence number of this message. children an array of Net::IMAP::ThreadMember objects for mail items that are children of this in the thread.

Attributes

[RW]	client_thread	The thread to receive exceptions.
[R]	greeting	Returns an initial greeting response from the server.
[R]	response_handlers	Returns all response handlers.
[R]	responses	Returns recorded untagged responses. For example: `imap.select("inbox") p imap.responses["EXISTS"][-1] #=> 2 p imap.responses["UIDVALIDITY"][-1] #=> 968263756`

Class Public methods

add_authenticator(auth_type, authenticator) Link

Adds an authenticator for #authenticate. auth_type is the type of authentication this authenticator supports (for instance, “LOGIN”). The authenticator is an object which defines a process() method to handle authentication with the server. See Net::IMAP::LoginAuthenticator, Net::IMAP::CramMD5Authenticator, and Net::IMAP::DigestMD5Authenticator for examples.

If auth_type refers to an existing authenticator, it will be replaced by the new one.

Class Net::IMAP < Object

IMAP Overview

Examples of Usage

List sender and subject of all recent messages in the default mailbox

Move all messages from April 2003 from “Mail/sent-mail” to “Mail/sent-apr03”

Thread Safety

Errors

References

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