Can I use post in express English?

If you use post, others will understand, but this statement is not authentic.

In English, "express delivery (parcel)" is generally used for:

① English expression of parcel

Example:

We can go out as soon as the package arrives.

As soon as the courier arrives, we will go out.

2 package ['p? k？ d？ American expression

Example:

The courier just brought you a package.

The courier just brought you a package.