This is the 279th most frequent German word.
per
The German word "per" means "via," "by," or "through."
Here, 'per' denotes the mode of delivery—'by mail'.
Die Bestellung wird per Post geliefert.
The order will be delivered by mail.
In this case, 'per' indicates the medium used for communication—'via email'.
Ich schicke dir die Dokumente per E-Mail.
I will send you the documents via email.
Here, 'per' shows the suggested method for registration—'by phone'.