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NAME

App::wsgetmail - Fetch mail from the cloud using webservices

SYNOPSIS

Run:

    wsgetmail [options] --config=wsgetmail.json

where wsgetmail.json looks like:

    {
    "client_id": "abcd1234-xxxx-xxxx-xxxx-1234abcdef99",
    "tenant_id": "abcd1234-xxxx-xxxx-xxxx-123abcde1234",
    "secret": "abcde1fghij2klmno3pqrst4uvwxy5~0",
    "global_access": 1,
    "username": "rt-comment@example.com",
    "folder": "Inbox",
    "stripcr": 0,
    "command": "/opt/rt5/bin/rt-mailgate",
    "command_args": "--url=http://rt.example.com/ --queue=General --action=comment",
    "command_timeout": 30,
    "action_on_fetched": "mark_as_read"
    }

Using App::wsgetmail as a library looks like:

    my $getmail = App::wsgetmail->new({config => {
      # The config hashref takes all the same keys and values as the
      # command line tool configuration JSON.
    }});
    while (my $message = $getmail->get_next_message()) {
        $getmail->process_message($message)
          or warn "could not process $message->id";
    }

DESCRIPTION

wsgetmail retrieves mail from a folder available through a web services API and delivers it to another system. Currently, it only knows how to retrieve mail from the Microsoft Graph API, and deliver it by running another command on the local system.

INSTALLATION

    perl Makefile.PL
    make
    make test
    sudo make install

wsgetmail will be installed under /usr/local/bin if you're using the system Perl, or in the same directory as perl if you built your own.

ATTRIBUTES

config

A hash ref that is passed to construct the mda and client (see below).

mda

An instance of App::wsgetmail::MDA created from our config object.

client_class

The name of the App::wsgetmail package used to construct the client. Default MS365.

client

An instance of the client_class created from our config object.

METHODS

process_message($message)

Given a Message object, retrieves the full message content, delivers it using the mda, and then executes the configured post-fetch action. Returns a boolean indicating success.

post_fetch_action($message)

Given a Message object, executes the configured post-fetch action. Returns a boolean indicating success.

CONFIGURATION

Configuring Microsoft 365 Client Access

To use wsgetmail, first you need to set up the app in Microsoft 365. Two authentication methods are supported:

Client Credentials

This method uses shared secrets and is preferred by Microsoft. (See Client credentials)

Username/password

This method is more like previous connections via IMAP. It is currently supported by Microsoft, but not recommended. (See Username/password)

This section walks you through each piece of configuration wsgetmail needs, and how to obtain it.

tenant_id

wsgetmail authenticates to an Azure Active Directory (AD) tenant. This tenant is identified by an identifier that looks like a UUID/GUID: it should be mostly alphanumeric, with dividing dashes in the same places as shown in the example configuration above. Microsoft documents how to find your tenant ID, and create a tenant if needed, in the "Set up a tenant" quickstart. Save this as the tenant_id string in your wsgetmail configuration file.

client_id

You need to register wsgetmail as an application in your Azure Active Directory tenant. Microsoft documents how to do this in the "Register an application with the Microsoft identity platform" quickstart, under the section "Register an application." When asked who can use this application, you can leave that at the default "Accounts in this organizational directory only (Single tenant)."

After you successfully register the wsgetmail application, its information page in your Azure account will display an "Application (client) ID" in the same UUID/GUID format as your tenant ID. Save this as the client_id string in your configuration file.

After that is done, you need to grant wsgetmail permission to access the Microsoft Graph mail APIs. Microsoft documents how to do this in the "Configure a client application to access a web API" quickstart, under the section "Add permissions to access Microsoft Graph." When selecting the type of permissions, select "Application permissions." When prompted to select permissions, select all of the following:

  • Mail.Read

  • Mail.Read.Shared

  • Mail.ReadWrite

  • Mail.ReadWrite.Shared

  • openid

  • User.Read

Configuring client secret authentication

We recommend you deploy wsgetmail by configuring it with a client secret. Client secrets can be granted limited access to only the mailboxes you choose. You can adjust or revoke wsgetmail's access without interfering with other applications.

Microsoft documents how to create a client secret in the "Register an application with the Microsoft identity platform" quickstart, under the section "Add a client secret." Take care to record the secret token when it appears; it will never be displayed again. It should look like a completely random string, not a UUID/GUID.

global_access

Set this to 1 in your wsgetmail configuration file.

secret

Set this to the secret token string you recorded earlier in your wsgetmail configuration file.

username

wsgetmail will fetch mail from this user's account. Set this to an email address string in your wsgetmail configuration file.

Configuring user+password authentication

If you do not want to use a client secret, you can also configure wsgetmail to authenticate with a traditional username+password combination. As noted above, this method is not recommended by Microsoft. It also does not work for systems with federated authentication enabled.

global_access

Set this to 0 in your wsgetmail configuration file.

username

wsgetmail will authenticate as this user. Set this to an email address string in your wsgetmail configuration file.

user_password

Set this to the password string for username in your wsgetmail configuration file.

Configuring the mail delivery command

Now that you've configured wsgetmail to access a mail account, all that's left is configuring delivery. Set the following in your wsgetmail configuration file.

folder

Set this to the name string of a mail folder to read.

stripcr

Set this to 1 to make wsgetmail convert the messages from the CRLF line-ending encoding to the LF line-ending encoding.

This emulates the fetchmail option of the same name, which enabled the stripcr option if an MDA was declared. The feature is similar, but you need to enable it explicitly in your configuration.

This option is helpful if you are forwarding email to a Linux utility that doesn't work with CRLF line-endings.

command

Set this to an executable command. You can specify an absolute path, or a plain command name which will be found from $PATH. For each email wsgetmail retrieves, it will run this command and pass the message data to it via standard input.

command_args

Set this to a string with additional arguments to pass to command. These arguments follow shell quoting rules: you can escape characters with a backslash, and denote a single string argument with single or double quotes.

command_timeout

Set this to the number of seconds the command has to return before timeout is reached. The default value is 30. Use "inf" for no timeout.

action_on_fetched

Set this to a literal string "mark_as_read" or "delete". For each email wsgetmail retrieves, after the configured delivery command succeeds, it will take this action on the message.

If you set this to "mark_as_read", wsgetmail will only retrieve and deliver messages that are marked unread in the configured folder, so it does not try to deliver the same email multiple times.

dump_messages

Set this to 1 to preserve the temporary files after processing.

When "debug" is also set the filenames will be reported on STDERR.

TESTING AND DEPLOYMENT

After you write your wsgetmail configuration file, you can test it by running:

    wsgetmail --debug --dry-run --config=wsgetmail.json

This will read and deliver messages, but will not mark them as read or delete them. If there are any problems, those will be reported in the error output. You can update your configuration file and try again until wsgetmail runs successfully.

Once your configuration is stable, you can configure wsgetmail to run periodically through cron or a systemd service on a timer.

ERRORS AND DIAGNOSTIC MESSAGES

wsgetmail sends warning, error, and debug messages to STDERR, while purely informational messages are sent to STDOUT. Operators may want to capture both output streams as a merged stream for diagnostic purposes. For example:

    wsgetmail --debug --dry-run --config=wsgetmail.json > wsgetmail.debug 2>&1

When the mail processing command exits with an error (non-zero) status the action_on_fetched is not performed on that message so that it will be processed on the next run.

Full output of the processing command is produced with --debug.

LIMITATIONS

Fetching from Multiple Folders

wsgetmail can only read from a single folder each time it runs. If you need to read multiple folders (possibly spanning different accounts), then you need to run it multiple times with different configuration.

If you only need to change a couple small configuration settings like the folder name, you can use the --options argument to override those from a base configuration file. For example:

    wsgetmail --config=wsgetmail.json --options='{"folder": "Inbox"}'
    wsgetmail --config=wsgetmail.json --options='{"folder": "Other Folder"}'

NOTE: Setting secret or user_password with --options is not secure and may expose your credentials to other users on the local system. If you need to set these options, or just change a lot of settings in your configuration, just run wsgetmail with different configurations:

    wsgetmail --config=account01.json
    wsgetmail --config=account02.json

Office 365 API Limits

Microsoft applies some limits to the amount of API requests allowed as documented in their Microsoft Graph throttling guidance. If you reach a limit, requests to the API will start failing for a period of time.

SEE ALSO

AUTHOR

Best Practical Solutions, LLC <modules@bestpractical.com>

LICENSE AND COPYRIGHT

This software is Copyright (c) 2015-2022 by Best Practical Solutions, LLC.

This is free software, licensed under:

The GNU General Public License, Version 2, June 1991