That isn't an issue controlled by Thunderbird. Instead, you should check with your email provider. The issue is complex, as the receiving email provider may also ban you. From my own experience, you will do better with a mass mailer, such as Mailchimp, and even there you have the possibility, though less, of being banned. I've been there and it's like fighting a ghost sometimes.

Thunderbird has no limits because it's just a program on your computer. But as a general guide I recall people used to find there was a limit of approximately 60 addresses when sending messages if you enter each address separately, but it may be to do with limits imposed by server. However, if you use lists (mail distribution lists) for most of the addresses any limit is imposed by whatever SMTP server you use.

Each mail account will connect to a specific server. That mail account may be provided by your ISP or a free one provided by eg: gmail or maybe you have purchased an email address. All servers have their limits on what you can send and the limit varies between servers. Some limit number of emails per hour and/or per 24 hour rolling period. Most do not permit large scale bulk emails and some offer that ability but you have to pay for it.

For example - Gmail limits - note there is a difference between limits sending via smtp 3rd party software and sending directly using webmail account. https://support.google.com/a/answer/166852 https://support.google.com/mail/answer/22839