Which of the following two variants is correct with reference to some email attachments?
- I am unable to open them.
- I am unable to open up them.
The first option is correct:
You could move the up in option two so that it reads I am unable to open them up, but the up is unnecessary in this sentence.
Brevity should be the aim of email communication, and he better expression would be I am unable to open it.
The meaning of this would be obvious to an email user, and the extra word 'up' doesn't add anything.