NAME¶
imapfilter_config
—
imapfilter configuration file
SYNOPSIS¶
$HOME/.imapfilter/config.lua
DESCRIPTION¶
imapfilter(1) uses the Lua programming language as
a configuration and extension language, therefore the configuration file is a
Lua script.
Although knowledge of Lua is not required to use
imapfilter(1), it is nonetheless recommended,
especially if one wants to extend it.
CONVENTIONS¶
A brief description of the Lua values and types mentioned hereafter in the
manual page follows:
- The nil is the type of the value
“nil”, whose main property is to be different from any other
value; usually it represents the absence of a useful value.
- The boolean is the type of the values
“true” and “false”. Both “nil”
and “false” make a condition false; any other value makes it
true.
- The type number represents real
numbers.
- The type string represents a sequence of
characters and can be defined using single quotes, double quotes or double
square brackets.
- The type table implements associative
arrays, that is, arrays that can be indexed not only with numbers, but
with any value.
- A function is a first-class value; it can
be stored in variables, passed as argument to other functions, and
returned as a result.
OPTIONS¶
Program's options are set using an already initialised
table named “options”, in the
following manner:
options.timeout = 120
options.namespace = false
options.charset = 'ISO-8859-1'
Available options are:
- cache
- When this option is enabled, parts of messages are cached locally in
memory to avoid being downloaded more than once. The cache is preserved
for the current session only. This variable takes a
boolean as a value. Default is
“true”.
- certificates
- When this option is enabled, the server certificate can be accepted and
stored, in order to validate the authenticity of the server in future
connections. This variable takes a
boolean as a value. Default is
“true”.
- charset
- Indicates to the server the character set of the strings for the searching
methods. This variable takes a string as
a value. By default no character set is set, and thus plain ASCII should
be assumed by the server.
- create
- According to the IMAP specification, when trying to write a message to a
non-existent mailbox, the server must send a hint to the client, whether
it should create the mailbox and try again or not. However some IMAP
servers don't follow the specification and don't send the correct response
code to the client. By enabling this option the client tries to create the
mailbox, despite of the server's response. This variable takes a
boolean as a value. Default is
“false”.
- close
- This option controls whether the currently selected mailbox is implicitly
closed at the end of each performed operation, thus removing all messages
that are marked deleted. This variable takes a
boolean as a value. Default is
“false”.
- crammd5
- When this option is enabled and the server supports the Challenge-Response
Authentication Mechanism (specifically CRAM-MD5), this method will be used
for user authentication instead of a plaintext password LOGIN. This
variable takes a boolean as a value.
Default is “true”.
- expunge
- Normally, messages are marked for deletion and are actually deleted when
the mailbox is closed. When this option is enabled, messages are expunged
immediately after being marked deleted. This variable takes a
boolean as a value. Default is
“true”.
- info
- When this options is enabled, a summary of the program's actions is
printed, while processing mailboxes. This variable takes a
boolean as a value. Default is
“true”.
- keepalive
- The time in minutes before terminating and re-issuing the IDLE command, in
order to keep alive the connection, by resetting the inactivity timeout of
the server. A standards compliant server must have an inactivity timeout
of at least 30 minutes. But it may happen that some IMAP servers don't
respect that, or some intermediary network device has a shorter timeout.
By setting this option the above problem can be worked around. This
variable takes a number as a value.
Default is “29” minutes.
- namespace
- When enabled, the program gets the namespace of the user's personal
mailboxes, and applies automatically the prefix and hierarchy delimiter to
any mailboxes residing on the mail server; the user must use the
‘/’ character as the delimiter and “” (ie.
nothing) as the prefix, regardless of the folder format of the mail
server. This must be disabled, if the user wants to manually specify
mailbox names (eg. because they are not part of the user's personal
namespace mailboxes). This variable takes
boolean as a value. Default is
“true”.
- recover
- With this option it is possible to control the recovery functionality,
which restores a session (the connection to the server and the IMAP state
at the time), after some unexpected event takes place. Currently there are
two types of events that can close abnormally a session, and finally cause
the program to terminate: network errors, and the IMAP BYE response which
a server can send anytime. When this option is set to “all”
the recovery function is triggered by both types of events, when set to
“errors” only in the case of network errors, and when set to
“none” the mechanism is completely disabled. Default is
“all”.
- starttls
- When this option is enabled and the server supports the IMAP STARTTLS
extension, a TLS connection will be negotiated with the mail server in the
beginning of the session. This variable takes a
boolean as value. Default is
“true”.
- subscribe
- By enabling this option new mailboxes that were automatically created, get
also subscribed; they are set active in order for IMAP clients to
recognize them. This variable takes a
boolean as a value. Default is
“false”.
- timeout
- The time in seconds for the program to wait for a mail server's response.
If not set, the client will block indefinitely. This variable takes a
number as a value. Default is
“60” seconds.
ACCOUNTS¶
Accounts are initialized using the
IMAP
()
function, and the details of the connection are defined using an account
table:
myaccount = IMAP {
server = 'imap.mail.server',
username = 'me',
password = 'secret',
ssl = 'ssl3'
}
An account
table must have the following
elements:
- server
- The hostname of the IMAP server to connect to. It takes a
string as a value.
- username
- User's name. It takes a string as a
value.
An account
table can also have the following
optional elements:
- password
- User's secret keyword. If a password wasn't supplied the user will be
asked to enter one interactively the first time it will be needed. It
takes a string as a value.
- port
- The port to connect to. It takes a number
as a value. Default is “143” for imap and
“993” for imaps.
- ssl
- Forces an imaps connection and specifies the SSL/TLS protocol to be used.
It takes a string as a value,
specifically one of: “ssl2”, “ssl3”,
“tls1”.
LISTING¶
The following methods can be used on an account to list mailboxes in a folder of
an account:
list_all
(folder)
- Lists all the available mailboxes in the
folder
(string), and returns a
table that contains
strings, the available mailboxes, and a
table that contains
strings, the available folders.
list_subscribed
(folder)
- Lists all the subscribed mailboxes in the
folder
(string), and returns a
table that contains
strings, the subscribed mailboxes, and a
table that contains
strings, the subscribed folders.
The following methods can be used on an account to list mailboxes, using
wildcards, in a folder of an account. The ‘*’ wildcard, matches
any character and the ‘%’ matches any character except the
folder delimiter, ie. non-recursively:
list_all
(folder,
mailbox)
- Lists all the available mailboxes in the
folder
(string) with the name
mailbox
(string), and returns a
table that contains
strings, the available mailboxes, and a
table that contains
strings, the available folders. Wildcards
may only be used in the mailbox argument.
list_subscribed
(folder,
mailbox)
- Lists all the subscribed mailboxes in the
folder
(string) with the name
mailbox
(string), and returns a
table that contains
strings, the subscribed mailboxes, and a
table that contains
strings, the subscribed folders.
Wildcards may only be used in the mailbox
argument.
Examples:
mailboxes, folders = myaccount:list_subscribed('myfolder')
mailboxes, folders = myaccount:list_all('myfolder/mysubfolder', '*')
MANIPULATING¶
The following methods can be used to manipulate mailboxes in an account:
create_mailbox
(name)
- Creates the name
(string) mailbox.
delete_mailbox
(name)
- Deletes the name
(string) mailbox.
rename_mailbox
(oldname,
newname)
- Renames the oldname
(string) mailbox to
newname
(string).
subscribe_mailbox
(name)
- Subscribes the name
(string) mailbox.
unsubscribe_mailbox
(name)
- Unsubscribes the name
(string) mailbox.
Examples:
myaccount:create_mailbox('mymailbox')
myaccount:subscribe_mailbox('mymailbox')
myaccount:unsubscribe_mailbox('myfolder/mymailbox')
myaccount:delete_mailbox('myfolder/mymailbox')
MAILBOXES¶
After an IMAP account has been initialized, mailboxes residing in that account
can be accessed simply as elements of the account
table:
If mailbox names don't only include letters, digits and underscores, or begin
with a digit, an alternative form must be used:
A mailbox inside a folder can be only accessed by using the alternative form:
myaccount['myfolder/mymailbox']
The methods that are available for an account (eg.
list_all
(),
create_mailbox
(), etc.) , are considered
keywords and must not be used as mailbox names, and the same also applies for
any string starting with an underscore, as they are considered reserved.
CHECKING¶
The following methods can be used to check the status of a mailbox:
check_status
()
-
The
check_status
() method gets the
current status of a mailbox, and returns four values of
number type: the total number of
messages, the number of recent messages, the number of unseen messages in
the mailbox, and the next UID to be assigned to a new message in the
mailbox.
enter_idle
()
- The
enter_idle
() method implements the
IMAP IDLE (RFC 2177) extension. By using this extension it's not necessary
to poll the server for changes to the selected mailbox (ie. using the
check_status
() method), but instead the
server sends an update when there is a change in the mailbox (eg. in case
of new mail). When the enter_idle
()
method has been called no more commands in the configuration file are
executed until an update is received, at which point the
enter_idle
() method returns. For the
enter_idle
() to work, the IDLE
extension has to be supported by the IMAP server. The
enter_idle
() method returns one value
of type boolean: “true” if
the IDLE extension is supported and there was a update in the mailbox, and
“false” if the IDLE extension is not supported, in which
case the method returns immediately.
Examples:
exist, unread, unseen, uidnext = myaccount.mymailbox:check_status()
update = myaccount.mymailbox:enter_idle()
SEARCHING¶
The searching methods in this subsection can be applied to any mailbox. They
return a special form of
table, that contains
the messages that match the searching method. This
table can be combined with other
tables using logic theory. There are three
available operations, that implement logical “or”, logical
“and” and logical “not”.
The logical “or” is implemented using the ‘+’
operator:
results = myaccount.mymailbox:is_unseen() +
myaccount.mymailbox:is_larger(100000)
The logical “and” is implemented using the ‘*’
operator:
results = myaccount.mymailbox:is_unseen() *
myaccount.mymailbox:is_larger(100000)
The logical “not” is implemented using the ‘-’
operator:
results = myaccount.mymailbox:is_unseen() -
myaccount.mymailbox:is_larger(100000)
The three logical operators can be combined in the same expression. The logical
“and” has higher precedence than the logical “or”
and the logical “not”, with the latter two having the same
precedence, and parentheses may be used to change this behaviour:
results = myaccount.mymailbox:is_unseen() +
myaccount.mymailbox:is_larger(100000) *
myaccount.mymailbox:contain_subject('test')
results = ( myaccount.mymailbox:is_unseen() +
myaccount.mymailbox:is_larger(100000) ) *
myaccount.mymailbox:contain_subject('test')
The returned
tables of the searching methods
can also be stored in variables and then further processed:
unseen = myaccount.myaccount:is_unseen()
larger = myaccount.mymailbox:is_larger(100000)
subject = myaccount.mymailbox:contain_subject('test')
results = unseen + larger * subject
A composite filter that includes one or more simple rules can be defined:
myfilter = function ()
return myaccount.mymailbox:is_unseen() +
myaccount.mymailbox:is_larger(100000) *
myaccount.mymailbox:contain_subject('test')
end
results = myfilter()
Composite filters can may be more dynamic by adding arguments:
myfilter = function (mailbox, size, subject)
return mailbox:is_unseen() +
mailbox:is_larger(size) *
mailbox:contain_subject(subject)
end
results = myfilter(myaccount.mailbox, 100000, 'test')
It is also possible to combine the searching methods in different mailboxes,
either at the same or different accounts, for example when the same actions
will be executed on messages residing in different mailboxes or accounts.
results = myaccount.mymailbox:is_unseen() +
myaccount.myothermailbox:is_larger(100000) +
myotheraccount.myothermailbox:contain_subject('test')
The following method can be used to get all messages in a mailbox:
select_all
()
- All messages.
The following methods can be used to search for messages that are in a specific
state:
is_answered
()
- Messages that have been answered.
is_deleted
()
- Messages that are marked for later removal.
is_draft
()
- Messages that have not completed composition.
is_flagged
()
- Messages that are flagged for urgent/special attention.
is_new
()
- Messages that are recently arrived (this session is the first to have been
notified about these messages) and have not been read.
is_old
()
- Messages that are not recently arrived (this session is not the first to
have been notified about these messages) and have not been read.
is_recent
()
- Messages that are recently arrived (this session is the first to have been
notified about these messages).
is_seen
()
- Messages that have been read.
is_unanswered
()
- Messages that have not been answered.
is_undeleted
()
- Messages that are not marked for later removal.
is_undraft
()
- Messages that have completed composition.
is_unflagged
()
- Messages that are not flagged for urgent/special attention.
is_unseen
()
- Messages that have not been read.
The following method can be used to search for messages that have a specific
flag set:
has_flag
(keyword)
- Messages with the specified keyword flag
(string) set.
The following methods can be used to search for messages based on their size:
is_larger
(size)
- Messages that are larger than the size
(number) in octets (bytes).
is_smaller
(size)
- Messages that are smaller than the size
(number) in octets (bytes).
The following methods can be used to search for messages based on their age:
is_newer
(age)
- Messages that are newer than the age
(number) in days.
is_older
(age)
- Messages that are older than the age
(number) in days.
The following methods can be used to search for messages based on their arrival
or sent date, in the “day-month-year” form, where day is the day
of the month as a decimal number (01-31), month is the abbreviated month (
“Jan”, “Feb”, “Mar”,
“Apr”, “May”, “Jun”,
“Jul”, “Aug”, “Sep”,
“Oct”, “Nov”, “Dec”) and year is the
year as decimal number including the century (eg. 2007):
arrived_before
(date)
- messages that have arrived before the
date
(string), where
date is in the
“day-month-year” form.
arrived_on
(date)
- Messages that have arrived on the date
(string), where
date is in the
“day-month-year” form.
arrived_since
(date)
- Messages that have arrived after the date
(string), where
date is in the
“day-month-year” form.
sent_before
(date)
- Messages that have been sent before the
date
(string), where
date is in the
“day-month-year” form.
sent_on
(date)
- Messages that have been sent on the date
(string), where
date is in the
“day-month-year” form.
sent_since
(date)
- Messages that have been sent after the
date
(string), where
date is in the
“day-month-year” form.
The following methods can be used to search for messages that contain a specific
word or phrase:
contain_bcc
(string)
- Messages that contain the string
(string) in the “Bcc”
header field.
contain_cc
(string)
- Messages that contain the string
(string) in the “Cc” header
field.
contain_from
(string)
- Messages that contain the string
(string) in the “From”
header field.
contain_subject
(string)
- Messages that contain the string
(string) in the “Subject”
header field.
contain_to
(string)
- Messages that contain the string
(string) in the “To” header
field.
contain_field
(field,
string)
- Messages that contain the string
(string) in the
field
(string) header field.
contain_body
(string)
- Messages that contain the string
(string) in the message body.
contain_message
(string)
- Messages that contain the string
(string) in the message.
The following methods can be used to search for messages that match a specific
regular expression pattern.
This way of searching is not supported by the IMAP protocol, and this means that
what actually happens under the hood, is that the relevant parts of all the
messages are downloaded and matched locally. It is therefore recommended to
use these methods with meta-searching (see following section), in order to
narrow down the set of messages that should be searched, and thus minimize
what will be downloaded.
Note that due to Lua using backslash ‘\’ as an escape character
for its strings, one has to double backslashes in order to insert a single
backslash inside a regular expression pattern:
match_bcc
(pattern)
- Messages that match the regular expression
pattern
(string) in the “Bcc”
header field.
match_cc
(pattern)
- Messages that match the regular expression
pattern
(string) in the “Cc” header
field.
match_from
(pattern)
- Messages that match the regular expression
pattern
(string) in the “From”
header field.
match_subject
(pattern)
- Messages that match the regular expression
pattern
(string) in the “Subject”
header field.
match_to
(pattern)
- Messages that match the regular expression
pattern
(string) in the “To” header
field.
match_field
(field,
pattern)
- Messages that match the regular expression
pattern
(string) in the
field
(string) header field.
match_header
(pattern)
- Messages that match the regular expression
pattern
(string) in the message header.
match_body
(pattern)
- Messages that match the regular expression
pattern
(string) in the message body.
match_message
(pattern)
- Messages that match the regular expression
pattern
(string) in the message.
The following method can be used to search for messages using user queries based
on the IMAP specification (RFC 3501 Section 6.4.4):
send_query
(criteria)
- Searches messages by sending an IMAP search query as described in the
search criteria
(string).
Examples:
results = myaccount.mymailbox:select_all()
results = myaccount.mymailbox:is_new()
results = myaccount.mymailbox:is_recent()
results = myaccount.mymailbox:is_larger(100000)
results = myaccount.mymailbox:is_older(10)
results = myaccount.mymailbox:has_flag('MyFlag')
results = myaccount.mymailbox:arrived_before('01-Jan-2007')
results = myaccount.mymailbox:sent_since('01-Jan-2007')
results = myaccount.mymailbox:contain_subject('test')
results = myaccount.mymailbox:contain_field('Sender', 'user@host')
results = myaccount.mymailbox:contain_body('hello world')
results = myaccount.mymailbox:match_from('.*(user1|user2)@host')
results = myaccount.mymailbox:send_query('ALL')
results = myaccount['mymailbox']:is_new()
results = myaccount['myfolder/mymailbox']:is_recent()
RESULTS¶
After one of more searching methods have been applied to one or more mailboxes,
the result contains all the necessary information, such as which messages
matched in which mailboxes. Using this result these messages can be either
searched further or processed in various way.
The results of the searching methods can be searched further on in the same way
as searching is done in mailboxes. The difference is that instead of doing the
search in the whole mailbox, ie. in all the messages, it is instead done only
to those messages that were returned in a previous search.
Examples:
results:match_message('^[Hh]ello world!?$')
myaccount.mymailbox:is_new():match_body('^[Ww]orld, hello!?$')
PROCESSING¶
The processing methods are applied to the results that searching returned.
The following method can be used to delete messages in a mailbox:
delete_messages
()
- Deletes the messages that matched.
The following methods can be used to copy and move messages in a mailbox at the
same or different accounts. If the destination mailbox is in a different
account than the source mailbox, then the messages are downloaded and then
uploaded to the destination:
copy_messages
(destination)
- Copies the messages to the destination,
which is a mailbox at an account.
move_messages
(destination)
- Moves the messages to the destination,
which is a mailbox at an account.
The following methods can be used to mark messages in a mailbox:
mark_answered
()
- Marks the messages as answered.
mark_deleted
()
- Marks the messages for later removal.
mark_draft
()
- Marks the messages as draft.
mark_flagged
()
- Marks the messages for urgent/special attention.
mark_seen
()
- Marks the messages as read.
unmark_answered
()
- Unmarks the messages that have been marked as answered.
unmark_deleted
()
- Unmarks the messages that have been marked for later removal.
unmark_draft
()
- Unmarks the messages that have been marked as draft.
unmark_flagged
()
- Unmarks the messages that have been marked for urgent/special attention.
unmark_seen
()
- Unmarks the messages that have been marked as read.
The following methods can be used to flag messages in a mailbox. The standard
system flags are “\Answered”, “\Deleted”,
“\Draft”, “\Flagged”, “\Seen”, while
if the server supports it, new user keywords may be defined:
add_flags
(flags)
- Adds the flags
(table that contains
strings) to the messages.
remove_flags
(flags)
- Removes the flags
(table that contains
strings) from the messages.
replace_flags
(flags)
- Replaces the flags
(table that contains
strings) of the messages.
Examples:
results:delete_messages()
results:copy_messages(myaccount.myothermailbox)
results:move_messages(myotheraccount.mymailbox)
results:mark_seen()
results:unmark_flagged()
results:add_flags({ 'MyFlag', '\\Seen' })
results:remove_flags({ '\\Seen' })
results:move_messages(myotheraccount['myfolder/mymailbox'])
MESSAGES¶
The messages that are residing in any mailbox can be also accessed, as a whole
or in parts. Messages can be accessed using their unique identifier (UID):
The UIDs of messages the user is interested in, are gained from the results of
searching:
results = account.INBOX:is_unseen()
for _, message in ipairs(results) do
mailbox, uid = table.unpack(message)
header = mailbox[uid]:fetch_header()
end
FETCHING¶
The following methods can be used to fetch parts of messages. The methods return
a
string. The downloaded message parts are
cached locally, so they can be reused inside the same program session:
fetch_message
()
- Fetches the header and body of the message.
fetch_header
()
- Fetches the header of the message.
fetch_body
()
- Fetches the body of the messages.
fetch_field
(field)
- Fetches the specified header field
(string) of the message.
fetch_part
(part)
- Fetches the specified part
(string) of the message.
The following methods can be used to fetch details about the state of a message:
fetch_flags
()
- Fetches the flags of the message. Returns a
table of
strings.
fetch_date
()
- Fetches the internal date of the message. Returns a
string.
fetch_size
()
- Fetches the size of the message. Returns a
number.
fetch_structure
()
- Fetches the body structure of the message. Returns a
table that has as keys the parts of the
message, and as values a table that has
one mandatory element, the type (string)
of the part, and two optional elements, the size
(number) and name
(string) of the part.
APPENDING¶
The following methods can be used to append a message to a mailbox:
append_message
(message)
- Appends the message
(string) to the mailbox.
append_message
(message,
flags,
date)
- Appends the message
(string) to the mailbox, setting the
specified flags
(table of
strings), as returned by
fetch_flags
(), and
date
(string), as returned by
fetch_date
().
Examples:
myaccount.mymailbox[2]:fetch_message()
myaccount.mymailbox[3]:fetch_field('subject')
myaccount.mymailbox[5]:fetch_part('1.1')
myaccount['mymailbox'][7]:fetch_message()
myaccount['myfolder/mymailbox'][11]:fetch_message()
myaccount.mymailbox:append_message(message)
FUNCTIONS¶
The following auxiliary functions are also available for convenience:
form_date
(days)
- Forms a date in “day-month-year” format that the system had
before the number of days
(number), and returns it as a
string.
get_password
(prompt)
- Displays the specified prompt
(string), and reads a password, while
character echoing is turned off. Returns that password as a
string.
become_daemon
(interval,
commands)
- Detaches the program from the controlling terminal and runs it in the
background as system daemon. The program will then repeatedly poll at the
specified interval
(number) in seconds. Each time the
program wakes up, the commands
(function) are executed.
become_daemon
(interval,
commands,
nochdir,
noclose)
- Detaches the program from the controlling terminal and runs it in the
background as system daemon. The program will then repeatedly poll at the
specified interval
(number) in seconds. Each time the
program wakes up, the commands
(function) are executed.
If nochdir
(boolean) is “true”, the
current working directory is not changed to the root directory
(/). If
noclose
(boolean) is “true”, the
standard input, standard output and standard error are not redirected to
/dev/null.
pipe_to
(command,
data)
- Executes the system's command
(string) and sends the
data
(string) to the standard input channel of
the subprocess. Returns a number, the
exit status of the child process.
pipe_from
(command)
- Executes the system's command
(string) and retrieves the data from the
standard output channel of the subprocess. Returns a
number, the exit status of the child
process, and a string, the output of the
child process.
regex_search
(pattern,
string)
- Implements Perl-compatible regular expressions (PCRE). The
pattern
(string) is a PCRE pattern. The
string
(string) is the subject string in which
the pattern is matched against. Returns at least a
boolean, that denotes if the match was
successful, and any captures which are of
string type. Note that due to Lua using
backslash ‘\’ as an escape character for its strings, one
has to double backslashes in order to insert a single backslash inside a
regular expression pattern:
Examples:
date = form_date(14)
password = get_password('Enter password: ')
become_daemon(600, myfunction)
status = pipe_to('mycommandline', 'mydata')
status, data = pipe_from('mycommandline')
success, capture = regex_search('^[PpCcRrEe]: (\\w)$', 'mystring')
EXAMPLES¶
See
samples/config.lua and
samples/extend.lua in the source code
distribution.
ENVIRONMENT¶
HOME
- User's home directory.
SEE ALSO¶
imapfilter(1)