I am porting scripts from Solaris to RHEL 5.x that contain mailx commands. It looks like Linux does not support the -r for return address?

On Solaris, mailx -r works, but on RHEL 5, it returns:
mailx: invalid option -- r

Is there an alternative for a return address in Linux? I would like to avoid changing all these scripts.

There is a similar post in this forum but there was no reply so I'm reposting this. I also searched in google and people were suggesting to use sendmail. I have mailx command in my scripts in lot of places so changing to sendmail involves lot of work. Can any one please suggest if there is any option in mailx command to support return address.