mRpostman

An IMAP Client for R

Overview

mRpostman is an easy-to-use IMAP client that provides tools for message searching, selective fetching of message attributes, mailbox management, attachment extraction, and several other IMAP features. The aim of this package is to pave the way for email data analysis in R. To do so, mRpostman makes extensive use of the {curl} package and the libcurl C library.

mRpostman’s official website: https://allanvc.github.io/mRpostman/

Cite mRpostman: A. V. C. Quadros, “mRpostman: An IMAP Client for R”, Journal of Open Research Software, vol. 12, no. 1, p. 4, 2024, doi: 10.5334/jors.480. http. Refer to citation("mRpostman").

IMPORTANT:

1. In version 0.9.0.0, mRpostman went trough substantial changes, including ones that have no backward compatibility with versions <= 0.3.1. A detailed vignette on how to migrate your mRpostman’s deprecated code to the new syntax is available at “Migrating old code to the new mRpostman’s syntax”.

2. Old versions of the libcurl C library ({curl}’s main engine) will cause the malfunction of this package. If your libcurl’s version is above 7.58.0, you should be fine. In case you intend to use OAuth 2.0 authentication, then you will need libcurl >= 7.65.0. To learn more about the OAuth 2.0 authentication in this package, refer to the “Using IMAP OAuth2.0 authentication in mRpostman” vignette.

3. Most mail providers discontinued less secure apps access. If it is still available and you are comfortable with this type of access you can enable this option for your account on your mail provider. Some providers, such as Yahoo Mail, also offer the option to generate password to be used by third-party apps such as mRpostman. The other option, as mentioned above, is to set up OAuth2 (two-factor authentication) in order to access your mailbox. Please also refer to the “Using IMAP OAuth2.0 authentication in mRpostman” vignette.

Providers and their IMAP urls

* For Office 365 accounts, the username should be set as [email protected] or [email protected] for example.

Introduction

From version 0.9.0.0 onward, mRpostman is implemented under the OO paradigm, based on an R6 class called ImapCon. Its derived methods, and a few independent functions enable the R user to perform a myriad of IMAP commands.

The package is divided in 8 groups of operations. Below, we present all the available methods and functions:

• configuration methods: configure_imap(), reset_url(), reset_username(), reset_password(), reset_verbose(), reset_use_ssl(), reset_buffersize(), reset_timeout_ms(), reset_xoauth2_bearer();
• server capabilities method: list_server_capabilities();
• mailbox operations methods: list_mail_folders(), select_folder(), examine_folder(), rename_folder(), create_folder(), list_flags();
• single-search methods: search_before(), search_since(), search_period(), search_on(), search_sent_before(),search_sent_since(), search_sent_period(), search_sent_on(), search_string(), search_flag(), search_smaller_than(), search_larger_than(), search_younger_than(), search_older_than();
• the custom-search method and its helper functions: search();
  • relational operators functions: AND(), OR();
  • criteria definition functions: before(), since(), on(), sent_before(), sent_since(), sent_on(), string(), flag(), smaller_than(), larger_than(), younger_than(), older_than();
• fetch methods: fetch_body(), fetch_header(), fetch_text(), fetch_metadata(), fetch_attachments_list(), fetch_attachments();
• attachments methods: list_attachments(), get_attachments(), fetch_attachments_list(), fetch_attachments();
• complementary methods: copy_msg(), move_msg(), esearch_min_id(), esearch_max_id(), esearch_count_msg(), delete_msg(), expunge(), add_flags(), remove_flags(), replace_flags().

Installation

# CRAN version
install.packages("mRpostman")

# Dev version
if (!require('remotes')) install.packages('remotes')
remotes::install_github("allanvc/mRpostman")

Basic Usage

1) Configure an IMAP connection and list the server’s capabilities

library(mRpostman)

# Outlook - Office 365
con <- configure_imap(url="imaps://outlook.office365.com",
                      username="[email protected]",
                      password=rstudioapi::askForPassword()
)

# other IMAP providers that were tested: Hotmail ("imaps://imap-mail.outlook.com"),
#  Gmail (imaps://imap.gmail.com), Yahoo (imaps://imap.mail.yahoo.com/), 
#  AOL (imaps://export.imap.aol.com/), Yandex (imaps://imap.yandex.com)

# Other non-tested mail providers should work as well

con$list_server_capabilities()

2) List mail folders and select “INBOX”

# Listing
con$list_mail_folders()

# Selecting
con$select_folder(name = "INBOX")

3) Search messages by date

res1 <- con$search_on(date_char = "02-Jan-2020")

res1

4) Customizing a search with multiple criteria

Executing a search by string:

# messages that contain either "@k-state.edu" OR "ksu.edu" in the "TO" header field
res2 <- con$search(OR(
  string(expr = "@k-state.edu", where = "TO"),
  string(expr = "@ksu.edu", where = "TO")
))

res2

5) Fetch messages’ text using single-search results

res3 <- con$search_string(expr = "Welcome!", where = "SUBJECT") %>%
  con$fetch_text(write_to_disk = TRUE) # also writes results to disk

res3

6) Attachments

You can list the attachments of one or more messages with:

1. the list_attachments() function:

con$search_since(date_char = "02-Jan-2020") %>%
  con$fetch_text() %>% # or with fetch_body()
  list_attachments() # does not depend on the 'con' object

… or more directly with:

2. fetch_attachments_list()

con$search_since(date_char = "02-Jan-2020") %>%
  con$fetch_attachments_list()

If you want to download the attachments of one or more messages, there are also two ways of doing that.

1. Using the get_attachments() method:

con$search_since(date_char = "02-Jan-2020") %>%
  con$fetch_text() %>% # or with fetch_body()
  con$get_attachments()

… and more directly with the

2. fetch_attachments() method:

con$search_since(date_char = "02-Jan-2020") %>%
  con$fetch_attachments()

Future Improvements

• add further IMAP features;
• eliminate the {stringr} dependency in REGEX;
• implement a progress bar in fetch operations;

Known bugs

• search results truncation: This is a libcurl’s known bug which causes the search results to be truncated when there is a large number of message ids returned. To circumvent this problem, you can set a higher buffersize value, increasing the buffer capacity, and verbose = TRUE for monitoring the server response for truncated results when executing a search. When possible, mRpostman tries to issue a warning for possible truncated values.

• verbose = TRUE malfunction on Windows: This seems to be related to the {curl} R package. When using the verbose = TRUE on Windows, the flow of information between the IMAP server and the R session presents an intermittent behavior, which causes it to not be shown on the console, or with a considerable delay.

• shared mailbox access not working: This seems to be another libcurl’s bug, although more tests need to be done to confirm it. It does not allow the user to connect to a shared mailbox. To circumvent this, if the shared mailbox has a password associated with it, you can try a direct regular connection.

• xoauth2_bearer SASL error: This is related to old libcurl’s versions which causes the access token to not be properly passed to the server. This bug was fixed in libcurl 7.65.0. The problem is that many Linux distributions, such as Ubuntu 18.04, still provide libcurl 7.58.0 in their official distribution (libcurl4-openssl-dev). If you use a newer Linux distro such as Ubuntu 20.04, you should be fine as the distributed libcurl’s version will be above 7.65.0. Another alternative is to use plain authentication instead of OAuth2.0.

License

This package is licensed under the terms of the GPL-3 License.

References

Crispin, M. (2003), INTERNET MESSAGE ACCESS PROTOCOL - VERSION 4rev1, RFC 3501, March 2003, http.

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.

Ooms, J. (2020), curl: A Modern and Flexible Web Client for R. R package version 4.3, http.

Quadros, A. V. C. mRpostman: An IMAP Client for R, Journal of Open Research Software, vol. 12, no. 1, p. 4, 2024, doi: 10.5334/jors.480. http.

Stenberg, D. Libcurl - The Multiprotocol File Transfer Library, http.