1.608: How do I make /var/spool/mail mountable?

In our cluster we share a /usr/local disk. We have a directory
/usr/local/spool/mail and /var/spool/mail is soft-linked to it.

From: fred@hal6000.thp.Uni-Duisburg.DE (Fred Hucht)

Several problems has been reported on sharing the mail directory via
NFS. The problems may occur when two or more sendmail daemons and/or
mail readers access a user's mail file simultanously, because of NFS'
file locking mechanism.

We use another method here: Every user has one line in his/her
$HOME/.forward file that reads

xxx@mainserver.domain.name

where xxx is the user node and mainserver.domain.name is the full
hostname of one of the machines. Then all incoming mail to all machines
is forwarded to mainserver, while mainserver ignores this line.