This prevented the letter (from) being sent.

[sitifan]

In the first of the following sentences "being sent" is a participle used Gerundively; in the second it is an actual Gerund or Verbal noun:--
1. This prevented the letter being sent.
2. This prevented the letter from being sent.
Source: https://www.google.com.tw/books/edition/Historical_English_and_Derivation/XxhMAAAAMAAJ?hl=en&gbpv=1&dq="This+prevented+the+letter+being+sent."&pg=PA169&printsec=frontcover

Is #1 still acceptable to native speakers?

 

[5jj]

It is to me.

 

[jutfrank]

If you're asking about native speakers in general, I'd guess probably not.

As much as I love the word 'Gerundively', the grammar analysis is terribly outdated. I wonder what you're getting out of this book.