You're given a sentence and your task is to classify whether the sentence is acceptable or not. Any sentence which is grammatically correct, has a naturalistic text, is written by a native speaker and which minimizes superfluous content is acceptable, otherwise unacceptable. If the sentence is acceptable then write "acceptable", otherwise "unacceptable".

Sam didn't pick those packages up until it had stopped raining which are to be mailed tomorrow.
unacceptable

Ellen conferred to Helen.
unacceptable

I haven't seen this sentence before.

acceptable