What is the effect when there is forgery of a signature in a negotiable instrument?

General Rule:

It does NOT render the instrument void. The signature is wholly inoperative, and no right to retain the instrument, or to give a discharge thereof, or to enforce payment thereof against any party to it, is acquired through or under such signature. (Cut‐off rule)

Exception:

1. If the party against whom it is sought to enforce such right is precluded from setting up forgery or want of authority. (Sec. 23)

2. Where the forged signature is not necessary to the holder’s title, in which case, the forgery may be disregarded (Sec. 48)