Hi Nancy
Thanks for your question about the word "per."
"Per" is out-of-date although it is still often used in phrases such as, as per your request/instruction/order or as per contract / as per our telephone conversation, etc. In modern English, and particularly when you write business documents, it is better to use a more personal phrase for example: as you requested / instructed / ordered, or if it is not possible to personalise the phrase then according to the contract / following our telephone conversation, would probably be the best alternatives.
Hope this answers your question.
Regards
Kevin
The Workplace English Training Team
Regards
Workplace English Training E-Magazine Team