Rust
Outlook -- Create Map of Folder Paths to IDs

Recursively descends folders and creates a hashtable of folder paths to IDs. This can be done once at the start of your program (or even less if the map is persisted to a file or database).
The reason this is necessary is because folder ID's need to be passed to the Outlook API, and an application will typically be working with folder paths.
Note: This example requires Chilkat v9.5.0.67 or greater.
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let mut success = false;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

let http = chilkat::Http::new();

// Our folder path --> ID map will be stored in this hash table.
let folder_map = chilkat::Hashtable::new();

// Use your previously obtained access token here:
// See the following examples for getting an access token:
//    Get Microsoft Graph OAuth2 Access Token (Azure AD v2.0 Endpoint).
//    Get Microsoft Graph OAuth2 Access Token (Azure AD Endpoint).
//    Refresh Access Token (Azure AD v2.0 Endpoint).
//    Refresh Access Token (Azure AD Endpoint).

http.set_auth_token("MICROSOFT_GRAPH_ACCESS_TOKEN");

let sb_response = chilkat::StringBuilder::new();

// Begin by getting the top-level folders.
http.clear_url_vars();
let _ = http.set_url_var("userPrincipalName", "chilkatsoft@outlook.com");
success = http.quick_get_sb("https://graph.microsoft.com/v1.0/users/{$userPrincipalName}/mailFolders", &sb_response).is_ok();
if (!success) && (http.last_status() == 0) {
    println!("{}", http.last_error_text());
    return;
}

let json = chilkat::JsonObject::new();
let _ = json.load_sb(&sb_response);
json.set_emit_compact(false);

println!("Status code = {}", http.last_status());
if http.last_status() != 200 {
    println!("{}", json.emit().unwrap_or_default());
    println!("Failed.");
}

// This is our queue/stack of unprocessed folder ID's
// The recursive nature of this example is that we get the 
// child folders for each folder ID in the idQueue, which may
// cause additional ID's to be added.  We continue  until the idQueue
// is empty.
let id_queue = chilkat::StringArray::new();

let sb_folder_path = chilkat::StringBuilder::new();
let sb_queue_entry = chilkat::StringBuilder::new();
let mut folder_name = String::new();
let mut folder_path = String::new();
let mut folder_id = String::new();

// Prime the map and idQueue with the top-level folders.
let mut i = 0;
let mut num_folders = json.size_of_array("value");
while i < num_folders {
    json.set_i(i);
    folder_name = json.string_of("value[i].displayName").unwrap_or_default();
    folder_id = json.string_of("value[i].id").unwrap_or_default();
    let _ = sb_folder_path.set_string("/");
    let _ = sb_folder_path.append(&folder_name);
    folder_path = sb_folder_path.get_as_string().unwrap_or_default();
    let _ = folder_map.add_str(&folder_path, &folder_id);
    println!("{} --> {}", folder_path, folder_id);

    // Push the folder path + id onto the idQueue.
    sb_queue_entry.clear();
    let _ = sb_queue_entry.set_nth(0, &folder_path, "|", false, false);
    let _ = sb_queue_entry.set_nth(1, &folder_id, "|", false, false);
    let _ = id_queue.append(&sb_queue_entry.get_as_string().unwrap_or_default());
    i = i + 1;
}

// Initial output:
// /Archive --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAG8XunwAAAA=
// /Deleted Items --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEKAAAA
// /Drafts --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEPAAAA
// /Inbox --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEMAAAA
// /Junk Email --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEiAAAA
// /Outbox --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgELAAAA
// /Sent Items --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEJAAAA
// 

// Process the idQueue until it becomes empty.  This is the recursive loop.
let mut parent_folder_path = String::new();
let mut parent_folder_id = String::new();
while id_queue.length() > 0 {
    let _ = sb_queue_entry.set_string(&id_queue.get_string(0).unwrap_or_default());
    let _ = id_queue.remove_at(0);

    parent_folder_path = sb_queue_entry.get_nth(0, "|", false, false).unwrap_or_default();
    parent_folder_id = sb_queue_entry.get_nth(1, "|", false, false).unwrap_or_default();

    let _ = http.set_url_var("id", &parent_folder_id);
    success = http.quick_get_sb("https://graph.microsoft.com/v1.0/users/{$userPrincipalName}/mailFolders/{$id}/childFolders", &sb_response).is_ok();
    if (!success) && (http.last_status() == 0) {
        println!("{}", http.last_error_text());
        return;
    }

    let _ = json.load_sb(&sb_response);
    if http.last_status() != 200 {
        println!("Status code = {}", http.last_status());
        println!("{}", json.emit().unwrap_or_default());
        println!("Failed.");
    }

    i = 0;
    num_folders = json.size_of_array("value");
    while i < num_folders {
        json.set_i(i);
        folder_name = json.string_of("value[i].displayName").unwrap_or_default();
        folder_id = json.string_of("value[i].id").unwrap_or_default();
        let _ = sb_folder_path.set_string(&parent_folder_path);
        let _ = sb_folder_path.append("/");
        let _ = sb_folder_path.append(&folder_name);
        folder_path = sb_folder_path.get_as_string().unwrap_or_default();
        let _ = folder_map.add_str(&folder_path, &folder_id);
        println!("{} --> {}", folder_path, folder_id);

        // Push the folder path + id onto the idQueue.
        sb_queue_entry.clear();
        let _ = sb_queue_entry.set_nth(0, &folder_path, "|", false, false);
        let _ = sb_queue_entry.set_nth(1, &folder_id, "|", false, false);
        let _ = id_queue.append(&sb_queue_entry.get_as_string().unwrap_or_default());
        i = i + 1;
    }

}

// The hash table of mail folder paths --> ID's can be persisted to XML and saved to a file or database (or anywhere..)
let sb_folder_map_xml = chilkat::StringBuilder::new();
let _ = folder_map.to_xml_sb(&sb_folder_map_xml);
let _ = sb_folder_map_xml.write_file("qa_data/outlook/folderMap.xml", "utf-8", false);

// The hash table can be restored from the serialized XML like this:
let ht2 = chilkat::Hashtable::new();
let sb2 = chilkat::StringBuilder::new();
let _ = sb2.load_file("qa_data/outlook/folderMap.xml", "utf-8");
let _ = ht2.add_from_xml_sb(&sb2);

// What's the ID for the folder "/Inbox/abc/subFolderA" ?
println!("id for /Inbox/abc/subFolderA = {}", ht2.lookup_str("/Inbox/abc/subFolderA").unwrap_or_default());

// Final output:

// /Archive --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAG8XunwAAAA=
// /Deleted Items --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEKAAAA
// /Drafts --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEPAAAA
// /Inbox --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEMAAAA
// /Junk Email --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEiAAAA
// /Outbox --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgELAAAA
// /Sent Items --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAgEJAAAA
// /Inbox/abc --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAL8huv8AAAA=
// /Inbox/xyz --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAL8huwEAAAA=
// /Inbox/abc/subFolderA --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAL8huwAAAQ==
// /Inbox/abc/subFolderB --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAL8huwMAAAA=
// /Inbox/abc/subFolderA/a --> AQMkADAwATM0MDAAMS1iNTcwLWI2NTEtMDACLTAwCgAuAAADsVyfxjDU406Ic4X7ill8xAEA5_vF7TKKdE6bGCRqXyl2PQAAAL8huwIAAAA=
// 

// ------------------------------------------------------------------------------------------------------
// This example applies to: Exchange Online | Office 365 | Hotmail.com | Live.com | MSN.com | Outlook.com | Passport.com
// 
// The Microsoft Graph Outlook Mail API lets you read, create, and send messages and attachments, 
// view and respond to event messages, and manage folders that are secured by Azure Active Directory 
// in Office 365. It also provides the same functionality in Microsoft accounts specifically 
// in these domains: Hotmail.com, Live.com, MSN.com, Outlook.com, and Passport.com.