clj-imap-observer

'clj-imap-observer' is a Clojure library which lets you create a com.sun.mail.imap.IdleManager in a more functional way.

Usage

1. Add project dependency

[com.markusaschl/clj-imap-observer "0.3.0"]

2. Import the namespace

(ns com.example.your-application
  (:require [com.markusaschl.imap-observer :as imap-observer]))

3. Place your configuration into a file

Write something like this into <your-project>/ressources/mail-properties.edn:

{:host "example.com",
 :username "user@example.com",
 :password "password",
 :imap-protocol "imaps",
 :session-properties
 {"mail.event.scope" "application"}}

4. Make an observer

(def observer (imap-observer/make-observer
                    (->> (clojure.java.io/resource "mail-properties.edn")
                         slurp
                         clojure.edn/read-string)
                    [{:name "INBOX"
                      :mode (:read-write imap-observer/folder-modes)
                      :on-folder-opened
                      (fn [folder-obj] (def ^:dynamic *folder*  folder-obj))
                      :on-message-added
                      (fn [messages]
                        (def ^:dynamic *messages*  messages))}]))

Options

The function imap-observer/make-observer takes two arguments, config-options and folder-options.

'config-options' is a map, which uses these keys:

• :imap-protocol
• :host
• :username
• :password
• and :session-properties

':session-properties' is also a map, which is then converted into a java.util.Property object, which in turn is passed to jakarta.mail.Session/getDefaultInstance. That happens in imap-observer/session

For a list of all the properties you can use, see the com.sun.mail.imap documentation.

':folder-options' is an array consisting of a map made of:

• :name
• :mode
• :on-message-added
• :on-message-removed
• :on-folder-opened

For example:

[{:name "INBOX"
  :mode (:read-write com.markusaschl.imap-observer/folder-modes)
  :on-message-added (fn [messages])}]

Notes

1. Posible :mode(s) are jakarta.mail.Folder/READ_ONLY or jakarta.mail.Folder/READ_WRITE. For convenience reasons, those two are exported as a map in imap-observer/folder-modes
2. :name is the name of an existing mailbox folder
3. The functions :on-messsage-added and :on-message-removed are called with an array of jakarta.mail.Message. See also jakarta.mail.Message
4. The function :on-folder-openend is called with the appropriate jakarta.mail.Folder object. See also jakarta.mail.Folder

Tips

Timeout

After a certain period of inactivity, the server closes the connection to the client. To fix a possible jakarta.mail.FolderClosedException when reading a folder or email, I offer this solution:

(let
    [ten-minutes (->> 1000 (* 60) (* 10))
     idle-agent (agent (->> (imap-observer/make-observer
                             (->> (clojure.java.io/resource "mail-properties.edn")
                                  slurp
                                  clojure.edn/read-string)
                             [{:name "INBOX"
                               :mode (:read-write imap-observer/folder-modes)
                               :on-message-added (fn [messages])}])))]

    (prn "starting execution")
    (while true
      (send idle-agent component/start)
      (Thread/sleep ten-minutes)
      (send idle-agent component/stop)
      (prn "restarting execution")))

Bugs

TODOs

• [ ] test connection success with GreenMail
• [ ] test function calls (:on-folder-opened, :on-message-added and :on-message-removed) with GreenMail

License

The MIT License (MIT)

Copyright © 2021 Markus Aschl

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.