Please note a govt dept will never send you an email with a request to tender or a purchase order. Tenders are advertised and you have to purchase or collect the tender document.
There are also scams where people copy emails of existing construction or bigger companies, but if you look at it closely, the emails are not the same and have additional names added.
We have received a purchase order from such a scammer and when we asked them to fill a credit application, we received a completed form with the ID's and signatures of the directors within an hour. Also copies of all the CIPIC documents. This for a listed company! A call to the financial director confirmed that this was a scam and the matter was handed over to the police.