Limits on contact lists
IM networks impose limits on the number of user names that can be added to a contact list. If your bot has a large number of users on a particular network, this can prevent you from accessing the presence for some of these users. In addition, Microsoft limits the number of people who can have a bot to their contact list.
Yahoo, Live Messenger, and AOL AIM all limit the size of your bot's contact list to 1000 names. You may send messages to more than 1000 users, but will be unable to retrieve reliable presence on your users once you reach this limit.
Live Messenger places an additional restriction on the number of people who are able to place your bot onto their contact list. Only 1500 people may add your bot to their contact list. After this number is reached, your bot will not appear online to additional users and may have trouble replying to or sending messages to the additional users.
Bots that add a Google Talk ID to their application will be subject to limits imposed by Google Talk. These limits do not apply to bots talking to Google Talk users using their @bot.im address.
Google Talk will begin to behave erratically once 600 users are on a contact list. Issues include the inability to add new users to the contact list and trouble accessing presence information for all users. Additionally, Google talk will not accept messages from users that have not been added to your contact list. In order to add a user to the contact list, we must first add that user to your bot's contact list. This means that once the contact limit is reached, you will be unable to send messages to additional users.
Twitter limits user IDs to following 2000 users. Any number of people can follow a twitter user, however. Once your bot reaches the limit of 2000 users followed, you will not be able to follow additional users. This primarily affects Direct messages, as a direct message may only be received from users you follow.
Microsoft and AOL have programs designed to lift these limits. If your bot reaches the limits set by the network, contact us and we can help get these limits removed.
Detailed information on the limitations of each network can be found in the article Table of Network Limits