For the .forward files to be an effective part of mail delivery, ensure that the following controls (mostly permissions settings) are correctly applied.
The .forward file must be writable only by the owner of the file. This restriction prevents other users from breaking security.
The paths that lead to the home directory must be owned and writable by root only. For example, if a .forward file is in /export/home/terry, /export and /export/home must be owned and writable by root only.
The actual home directory should be writable only by the user.
The .forward file cannot be a symbolic link, and this file cannot have more than one hard link.