I copied Will in to an email.
 I ran hurriedly away.
 He jumped immediately up.
An infinitive verb, especially those we split, have two parts: the particle to and a base verb. Like this,
Your friend's sentence above () does not have an infinitive verb. The phrase to an email is made up of the preposition to (which, by the way, looks like the particle to) and the noun email. There was no splittin' going on.
As for examples  and , they have phrasal verbs. Those are verbs that have two parts. They consist of a verb and an adverb or a preposition. For example, run away and jump up. It's OK to split them - if they can be split.
Now, going back to sentence , the question is, is copied in to correct? Well, Microsoft uses the phrase copy into; moreover, into means motion to or towards, and it answers the question where?
 I copied Will into an email.
Learn more here: Into/In To; Onto/In To
All the best.