How many people can you invite on Twitter through email at one time?

[Julian]

I want to invite my philosophy class to follow me on twitter, but there are about 100 emails. I don't want to put all 100 emails, but Twitter not invite them all. Because Twitter will sometimes say that everything is fine but not invite everyone.
The emails are in excel

[Danatlive]

If you click on Find Me in the top right of the page and then click the second tab along 'Find on other networks' click on the email provider you use and it automatically finds all your contacts who are on twitter.