NAME

wsgetmail - get mail from cloud 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",
"command": "/opt/rt5/bin/rt-mailgate",
"command_args": "--url=http://rt.example.com/ --queue=General --action=comment",
"action_on_fetched": "mark_as_read"
}

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.

ARGUMENTS

• --config, --configuration, -c

  Path of the primary wsgetmail JSON configuration file to read. This argument is required. The configuration file is documented in the next section.

• --options

  A string with a JSON object in the same format as the configuration file. Configuration in this object will override the configuration file. You can use this to extend a base configuration. For example, given the configuration in the synopsis above, you can process a second folder the same way by running:

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

• --verbose, --debug, -v

  Log additional information about each mail API request and any problems delivering mail.

• --dry-run

  Read mail and deliver it to the configured command, but don't run the configured action_on_fetched like deleting messages or marking them as read.

• --help, -h

  Show this help documentation.

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 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.

• 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.

• 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.

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.

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.

AUTHOR

Best Practical Solutions, LLC modules@bestpractical.com

LICENSE AND COPYRIGHT

This software is Copyright (c) 2015-2020 by Best Practical Solutions, LLC.

This is free software, licensed under:

The GNU General Public License, Version 2, June 1991