ImapCon: An IMAP Connection Class

Description

Configure an IMAP connection using the ImapCon R6 class.

Arguments

Methods

Public methods

Method `new()`

Configure and create a new IMAP connection.

Usage

ImapCon$new(
  url,
  username,
  password = NULL,
  xoauth2_bearer = NULL,
  use_ssl = TRUE,
  verbose = FALSE,
  buffersize = 16000,
  timeout_ms = 0,
  ...
)

Arguments

url: A character string containing the IMAP server address

username

A character string containing the username.

password

A character string containing the user's password.

xoauth2_bearer

A character string containing the oauth2 bearer token.

use_ssl

A logical indicating the use or not of Secure Sockets Layer encryption when connecting to the IMAP server. Default is TRUE.

verbose

If FALSE, mutes the flow of information between the server and the client. Default is FALSE.

buffersize

The size in bytes for the receive buffer. Default is 16000 bytes or 16kb, which means it will use the libcurl's default value. According to the libcurl's documentation, the maximum buffersize is 512kb (or 512000 bytes), but any number passed to buffersize is treated as a request, not an order.

timeout_ms

Time in milliseconds (ms) to wait for the execution or re-execution of a command. Default is 0, which means that no timeout limit is set.

...

Further curl parameters (see curl::curl_options) that can be used with the IMAP protocol. Only for advanced users.

Returns

A new `ImapCon` object.

Method `reset_url()`

Reset the previously informed url

Usage

ImapCon$reset_url(x)

Arguments

x: A character string containing a new url to be set.

Method `reset_username()`

Reset the previously informed username

Usage

ImapCon$reset_username(x)

Arguments

x: A character string containing a new username to be set.

Method `reset_use_ssl()`

Reset the previously informed use_ssl parameter

Usage

ImapCon$reset_use_ssl(x)

Arguments

x: A logical indicating the use or not of Secure Sockets Layer encryption when connecting to the IMAP server. Default is TRUE.

Method `reset_verbose()`

Reset the previously informed verbose parameter

Usage

ImapCon$reset_verbose(x)

Arguments

x: If FALSE, mutes the flow of information between the server and the client.

Method `reset_buffersize()`

Reset the previously informed buffersize parameter

Usage

ImapCon$reset_buffersize(x)

Arguments

x: The size in bytes for the receive buffer. Default is 16000 bytes or 16kb, which means it will use the libcurl's default value. According to the libcurl's documentation, the maximum buffersize is 512kb (or 512000 bytes), but any number passed to buffersize is treated as a request, not an order.

Method `reset_timeout_ms()`

Reset the previously informed buffersize parameter

Usage

ImapCon$reset_timeout_ms(x)

Arguments

x: Time in milliseconds (ms) to wait for the execution or re-execution of a command. Default is 0, which means that no timeout limit is set.

Method `reset_password()`

Reset the previously informed password

Usage

ImapCon$reset_password(x)

Arguments

x: A character string containing the user's password.

Method `reset_xoauth2_bearer()`

Reset the previously informed oauth2 bearer token

Usage

ImapCon$reset_xoauth2_bearer(x)

Arguments

x: A character string containing the oauth2 bearer token.

Method `list_server_capabilities()`

List the server's IMAP capabilities.

Usage

ImapCon$list_server_capabilities(retries = 1)

Arguments

retries: Number of attempts to connect and execute the command. Default is 1.

Returns

A character vector containing the server's IMAP capabilities.

Examples

\dontrun{
cap <- con$list_server_capabilities()
cap
}

Method `list_mail_folders()`

List mail folders in a mailbox.

Usage

ImapCon$list_mail_folders(retries = 1)

Arguments

retries: Number of attempts to connect and execute the command. Default is 1.

Returns

A list containing the mail folder names and their inherent structure.

Examples

\dontrun{
folders <- con$list_mail_folders()
folders
}

Method `select_folder()`

Select a mail folder.

Usage

ImapCon$select_folder(name, mute = FALSE, retries = 1)

Arguments

name: A string containing the name of an existing mail folder on the user's mailbox.

mute

A logical. If TRUE, mutes the confirmation message when the command is successfully executed. Default is FALSE.

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A list containing the mail folder names and their inherent structure.

Examples

\dontrun{
con$select_mail_folder(name = "INBOX")
}

Method `examine_folder()`

Examine the number of messages in a mail folder.

Usage

ImapCon$examine_folder(name = NULL, retries = 1)

Arguments

name: A character string containing the name of an existing mail folder on the user's mailbox. If no name is passed, the command will be executed using the previously selected mail folder name.

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A vector (with names "EXISTS" and "RECENT") containing the number of messages in each category.

Examples

\dontrun{
con$select_folder(name = "INBOX")
con$examine_folder()
# or directly:
con$examine_folder("Sent")
}

Method `create_folder()`

Create a new mail folder.

Usage

ImapCon$create_folder(name, mute = FALSE, retries = 1)

Arguments

name: A string containing the name of the new mail folder to be created.

mute

A logical. If TRUE, mutes the confirmation message when the command is successfully executed. Default is FALSE.

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

TRUE in case the operation is successful.

Examples

\dontrun{
con$create_folder(name = "New Folder Name")
}

Method `rename_folder()`

Rename a mail folder.

Usage

ImapCon$rename_folder(
  name = NULL,
  new_name,
  reselect = TRUE,
  mute = FALSE,
  retries = 1
)

Arguments

name: A string containing the name of the new mail folder to be renamed. If no name is passed, the command will be executed using the previously selected mail folder name.

new_name

A string containing the new name to be assigned.

reselect

A logical. If TRUE, calls select_folder(name = to_folder) under the hood before returning the output. Default is TRUE.

mute

A logical. If TRUE, mutes the confirmation message when the command is successfully executed. Default is FALSE.

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

TRUE in case the operation is successful.

Examples

\dontrun{
con$select_folder(name = "Folder A")
con$rename_folder(new_name = "Folder B")
# or directly:
con$rename_folder(name = "Folder A", new_name = "Folder B")
}

Method `list_flags()`

List flags in a selected mail folder

Usage

ImapCon$list_flags(retries = 1)

Arguments

retries: Number of attempts to connect and execute the command. Default is 1.

Returns

TRUE in case the operation is successful.

Examples

\dontrun{
con$select_folder(name = "INBOX")
con$list_flags()
}

Method `search()`

Execute a custom search

Usage

ImapCon$search(
  request,
  negate = FALSE,
  use_uid = FALSE,
  esearch = FALSE,
  retries = 1
)

Arguments

request: A string directly specifying what to search or constructed by a combination of relational-operator-helper-functions OR and AND, and criteria helper functions such as before, since, on, sent_before, sent_since, sent_on, flag, string, smaller_than, larger_than, younger_than, or younger_than.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERIA". Default is FALSE.

use_uid

Default is FALSE. In this case, results will be presented as message sequence numbers. A message sequence number is a message's relative position to the oldest message in a mail folder. It may change after deleting or moving messages. If a message is deleted, sequence numbers are reordered to fill the gap. If TRUE, the command will be performed using the "UID" or unique identifier, and results are presented as such. UIDs are always the same during the life cycle of a message in a mail folder.

esearch

A logical. Default is FALSE. If the IMAP server has ESEARCH capability, it can be used to optimize search results. It will condense the results: instead of writing down the whole sequences of messages' ids, such as {1 2 3 4 5}, it will be presented as {1:5}, which decreases transmission costs. This argument can be used along with buffersize to avoid results stripping. Check if your IMAP server supports ESEARCH with ImapCon$list_server_capabilities().

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A list containing the flags (character vector), the permanent flags (character vector), and an indication if custom flags are allowed by the server (logical vector).

Examples

\dontrun{
con$select_folder(name = "INBOX")
# ex1
con$search(OR(before(date_char = "17-Apr-2015"),
              string(expr = "John", where = "FROM")))
# ex2
con$search(AND(smaller_than(size = "512000"),
               string(expr = "John", where = "FROM"),
               string(expr = "@ksu.edu", where = "CC")))
}

Method `search_larger_than()`

Search by size (LARGER)

Usage

ImapCon$search_larger_than(
  size,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

size: An integer specifying the size in bytes to be used as the search criterion.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
# search for messages with size larger than 512Kb
con$search_larger_than(size = 512000))
}

Method `search_smaller_than()`

Search by size (SMALLER)

Usage

ImapCon$search_smaller_than(
  size,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

size: An integer specifying the size in bytes to be used as the search criterion.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for messages with size smaller than 512Kb
con$search_smaller_than(size = 512000))
}

Method `search_before()`

Search by internal date (BEFORE)

Usage

ImapCon$search_before(
  date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for messages with date before "02-Jan-2020", presenting the
# .. results as unique identifiers (UID)
con$search_before(date = "02-Jan-2020", use_uid = TRUE)
}

Method `search_since()`

Search by internal date (SINCE)

Usage

ImapCon$search_since(
  date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format. POSIX* like objects, since IMAP servers use this uncommon date format. POSIX* like, since IMAP servers like this not so common date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for messages with date since "02-Jan-2020", presenting the
# .. results as unique identifiers (UID)
con$search_since(date = "02-Jan-2020", use_uid = TRUE)
}

Method `search_on()`

Search by internal date (ON)

Usage

ImapCon$search_on(
  date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for messages received on date "02-Jan-2020", presenting the
#... results as unique identifiers (UID)
con$search_on(date = "02-Jan-2020", use_uid = TRUE)
}

Method `search_period()`

Search by internal date (Period)

Usage

ImapCon$search_period(
  since_date_char,
  before_date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

since_date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

before_date_char

A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for all messages in the mail folder, EXCEPT (negate = TRUE) by
#... those received between the dates "02-Jan-2020" and "22-Mar-2020"
con$search_period(since_date_char = "02-Jan-2020",
                  before_date_char = "22-Mar-2020",
                  negate = TRUE))
}

Method `search_sent_before()`

Search by origination date (RFC 2822 Header - SENT BEFORE)

Usage

ImapCon$search_sent_before(
  date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
# search for messages with date before "02-Jan-2020", presenting the
# .. results as unique identifiers (UID)
con$search_sent_before(date = "02-Jan-2020", use_uid = TRUE)
}

Method `search_sent_since()`

Search by origination date (RFC 2822 Header - SENT SINCE)

Usage

ImapCon$search_sent_since(
  date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
# search for messages with date before "02-Jan-2020", presenting the
# .. results as unique identifiers (UID)
con$search_sent_since(date = "02-Jan-2020", use_uid = TRUE)
}

Method `search_sent_on()`

Search by origination date (RFC 2822 Header - SENT ON)

Usage

ImapCon$search_sent_on(
  date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for messages received on date "02-Jan-2020", presenting the
#... results as unique identifiers (UID)
con$search_sent_on(date = "02-Jan-2020", use_uid = TRUE)
}

Method `search_sent_period()`

Search by origination date (RFC 2822 Header - SENT Period)

Usage

ImapCon$search_sent_period(
  since_date_char,
  before_date_char,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

since_date_char: A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

before_date_char

A character string with format "DD-Mon-YYYY", e.g. "01-Apr-2019". We opt not to use Date or POSIX* like objects, since IMAP servers use this uncommon date format.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for all messages in the mail folder, EXCEPT (negate = TRUE) by
#... those received between the dates "02-Jan-2020" and "22-Mar-2020"
con$search_sent_period(since_date_char = "02-Jan-2020",
                  before_date_char = "22-Mar-2020",
                  negate = TRUE))
}

Method `search_flag()`

Search by flag(s)

Usage

ImapCon$search_flag(
  name,
  negate = FALSE,
  use_uid = FALSE,
  esearch = FALSE,
  retries = 1
)

Arguments

name: A string containing one or more flags to search for. Use ImapCon$list_flags() to list the flags in a selected mail folder.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for all messages in the mail folder that are marked as "SEEN" AND
#.. "ANSWERED"
con$search_flag(name = c("SEEN", "ANSWERED"))
}

Method `search_older_than()`

Search WITHIN a specific time (OLDER)

Usage

ImapCon$search_older_than(
  seconds,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

seconds: An integer specifying the number of seconds to be used as the search criterion.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for all messages received in the last hour (not older than 3600 seconds)
con$search_older_than(seconds = 3600, negate = TRUE)
}

Method `search_younger_than()`

Search WITHIN a specific time (YOUNGER)

Usage

ImapCon$search_younger_than(
  seconds,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

seconds: An integer specifying the number of seconds to be used as the search criterion.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

retries

Number of attempts to connect and execute the command. Default is 1.

Returns

A numeric vector containing the message ids.

Examples

\dontrun{
con$select_folder(name = "INBOX")
# search for all messages received in the last hour (younger than 3600 seconds)
con$search_younger_than(seconds = 3600)
}

Method `search_string()`

Search by string or expression

Usage

ImapCon$search_string(
  expr,
  where,
  negate = FALSE,
  use_uid = FALSE,
  flag = NULL,
  esearch = FALSE,
  retries = 1
)

Arguments

expr: A character string specifying the word or expression to search for in messages.

where

A mandatory character string specifying in which message's Section or Header Field to search for the provided string.

negate

If TRUE, negates the search and seeks for "NOT SEARCH CRITERION". Default is FALSE.

use_uid

flag

An optional argument that sets one or more flags as an additional filter to the search. Use ImapCon$list_flags() to list the flags in a selected mail folder. Default is NULL.

esearch

A logical. Default is FALSE. If the IMAP server has ESEARCH capability, it can be used to optimize search results. It will condense the result

References

ImapCon$search_string(): Heinlein, P. and Hartleben, P. (2008). The Book of IMAP: Building a Mail Server with Courier and Cyrus. No Starch Press. ISBN 978-1-59327-177-0.

ImapCon$get_attachments(): Troost, R., Dorner, S., and K. Moore (1997), Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field, RFC 2183, August 1997, https://www.rfc-editor.org/rfc/rfc2183.

ImapCon$fetch_attachments(): Troost, R., Dorner, S., and K. Moore (1997), Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field, RFC 2183, DOI 10.17487/RFC2183, August 1997, https://www.rfc-editor.org/rfc/rfc2183.

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Description

Arguments

Methods

Public methods

Method new()

Usage

Arguments

Returns

Method reset_url()

Usage

Arguments

Method reset_username()

Usage

Arguments

Method reset_use_ssl()

Usage

Arguments

Method reset_verbose()

Usage

Arguments

Method reset_buffersize()

Usage

Arguments

Method reset_timeout_ms()

Usage

Arguments

Method reset_password()

Usage

Arguments

Method reset_xoauth2_bearer()

Usage

Arguments

Method list_server_capabilities()

Usage

Arguments

Returns

Examples

Method list_mail_folders()

Usage

Arguments

Returns

Examples

Method select_folder()

Usage

Arguments

Returns

Examples

Method examine_folder()

Usage

Arguments

Returns

Examples

Method create_folder()

Usage

Arguments

Returns

Examples

Method rename_folder()

Usage

Arguments

Returns

Examples

Method list_flags()

Usage

Arguments

Returns

Examples

Method search()

Usage

Arguments

Returns

Examples

Method search_larger_than()

Usage

Arguments

Returns

Examples

Method search_smaller_than()

Usage

Method `new()`

Method `reset_url()`

Method `reset_username()`

Method `reset_use_ssl()`

Method `reset_verbose()`

Method `reset_buffersize()`

Method `reset_timeout_ms()`

Method `reset_password()`

Method `reset_xoauth2_bearer()`

Method `list_server_capabilities()`

Method `list_mail_folders()`

Method `select_folder()`

Method `examine_folder()`

Method `create_folder()`

Method `rename_folder()`

Method `list_flags()`

Method `search()`

Method `search_larger_than()`

Method `search_smaller_than()`

Method `search_before()`

Method `search_since()`

Method `search_on()`

Method `search_period()`

Method `search_sent_before()`

Method `search_sent_since()`

Method `search_sent_on()`

Method `search_sent_period()`

Method `search_flag()`

Method `search_older_than()`

Method `search_younger_than()`

Method `search_string()`