Technical Implementation and Limitations of Sending Messages via Username in Telegram Bots

Overview of Telegram Bot Message Sending Mechanism

The Telegram Bot API, serving as the official interface for developers on the Telegram platform, implements message sending functionality with strict permission controls and privacy protection mechanisms. According to API specifications, sending private messages requires the chat_id parameter, which serves as the unique numeric identifier for users or groups.

Technical Limitations of Username-Based Message Sending

Within the Telegram Bot API, fundamental restrictions exist when attempting to send messages directly using usernames (formatted as @username). The API design, prioritizing privacy protection, prevents bots from arbitrarily sending messages to users without prior interaction. This limitation manifests in several aspects:

• Bots can only send messages to users who have initiated the /start command
• Username usage is restricted to channels and groups where the bot possesses administrator privileges
• Private conversations mandate the use of numeric chat_id identifiers

Username to User ID Conversion Methods

While the official API lacks direct username resolution capabilities, third-party tools provide conversion functionality. The telegram-cli project, specifically, offers the resolve_username command, which resolves usernames into corresponding user information.

Command execution example:

> resolve_username example_user

The returned result contains comprehensive user information:

{
  "user": {
    "username": "example_user",
    "id": "$010000006459670b02c0c7fd66d44708",
    "peer_type": "user",
    "peer_id": 191322468,
    "first_name": "Example"
  }
}

Extracting the peer_id field from the returned data provides the numeric user ID necessary for subsequent message transmission.

ID Acquisition Through User Interaction

When users initially interact with a bot, the system generates corresponding chat_id identifiers. The following procedure enables retrieval of this identifier:

1. User sends any message to the bot
2. Access https://api.telegram.org/bot<Bot_token>/getUpdates
3. Locate the result->message->chat->id field within the returned data

The obtained chat_id can be permanently stored for future message sending operations.

Python Implementation Example

The following code demonstrates message sending implementation using the telepot library:

import telepot
import json

# Initialize bot
bot = telepot.Bot('YOUR_BOT_TOKEN')

# Obtain user ID via getUpdates
def get_user_id(username):
    updates = bot.getUpdates()
    for update in updates:
        if 'message' in update:
            user = update['message']['from']
            if user.get('username') == username:
                return user['id']
    return None

# Message sending function
def send_message_to_user(username, message):
    user_id = get_user_id(username)
    if user_id:
        bot.sendMessage(user_id, message)
        return True
    return False

# Usage example
if send_message_to_user('target_user', 'Hello from bot!'):
    print("Message sent successfully")
else:
    print("User not found or no prior interaction with bot")

Privacy Protection and Technical Ethics Considerations

Telegram's design philosophy emphasizes user privacy protection, with restrictions on bot-initiated user contact representing a concrete manifestation of this principle. Developers implementing related functionality should consider:

• Respecting user preferences, sending messages only after obtaining explicit authorization
• Properly safeguarding acquired user data
• Adhering to Telegram platform terms of service and usage agreements

Alternative Approaches and Best Practices

In practical applications, the following strategies are recommended:

• Guiding users to proactively interact with bots to establish connections
• Implementing user authorization mechanisms with clear communication about message purposes
• Considering official Inline mode for scenarios requiring proactive notifications
• Regularly purging data of inactive users

Through thoughtful technical solution design and rigorous privacy protection measures, developers can meet business requirements while fully respecting user rights and platform regulations.