Hi Carey,
Here is what they put.
Help > Participating in a Group > Posting
Is there a limit on how often I can post?
Yes, there are a few ways in which posting frequency is limited. One limits the number of messages posted to a single group within a short period of time. If that limit is reached, posting to that group will be frozen temporarily and you'll be instructed to post again later.
Another limits the number of messages a single user can post via email in a short period of time. If that limit is reached, your posting account will be disabled. If your account has been disabled, you can click the "contact us" link below and request that your account be reactivated. We'll review your request, and let you know what we decide.
We may also limit the number of messages a single user or computer can post via our website in a short period of time. If that limit is reached, posting will be frozen temporarily and you'll be instructed to post again later.
Please note, we are unable to provide the exact numbers that trigger these posting limits as the limits are subject to change.
These limits are to protect the users of our service and their email accounts, our groups, and the Usenet community from poorly configured auto-responders, spammers, robots, and trolls.