What does this mean: question about Twitter?

[هاهاها]

"This person is on Twitter, but isn't yet findable by email.
Let them know you'd like to follow them."

Does this mean they already have twitter accounts but their emails aren't publicly shown? I'm asking this because I accidentally sent twitter invites to two teachers to the school I'm going to next term! I've already apologized to one teacher because I need him to answer an important question in the email I sent to him yesterday. Is there any way I can cancel the invites?

[nezzy]

it means:
this person is on twitter
but they cant find their E-mail
notify the person you wanna be a sheep.

no theres no cancel invites button