port-i386: /var/mail/simons created with mode 660: Why?

Subject: /var/mail/simons created with mode 660: Why?
To: None <port-i386@netbsd.org>
From: Peter Simons+mail.list.netbsd.port-i386 <simons@cys.de>
List: port-i386
Date: 05/31/1999 10:10:49

My NetBSD 1.4 keeps confusing me. When I receive e-mail to my normal
mailbox, the mailbox is created being group readable and writable 

 | root@peti:/var/mail# ls -la
 | total 10
 | drwxr-xr-x   2 root    wheel   512 May 31 10:09 .
 | drwxr-xr-x  19 root    wheel   512 May 28 14:23 ..
 | -rw-rw----   1 simons  wheel  2457 May 31 10:09 simons

and I have no idea why. Anyone else?

	-peter