cannot open /etc/mail/local-host-names

Recently I added a new hostname to /etc/mail/local-host-names and bounced sendmail:

svcadm restart sendmail.

But sendmail didn't come up and started logging these errors in /var/adm/messages:

May 13 14:21:50 mailserver1 sendmail[19725]: [ID 801593 mail.crit] NOQUEUE: SYSERR(root): /etc/mail/sendmail.cf: line 80: fileclass: cannot open '/etc/mail/loca
l-host-names': Group writable directory
May 13 14:21:50 mailserver1 sendmail[19725]: [ID 801593 mail.crit] NOQUEUE: SYSERR(root): /etc/mail/sendmail.cf: line 561: fileclass: cannot open '/etc/mail/tru
sted-users': Group writable directory

We engaged unix team and they did something and the error changed to:

May 13 14:33:38 tsgp1403 sendmail[13585]: [ID 801593 mail.alert] n4DHe0KO027983: queueup: cannot create ./tfn4DHe0KO027983, uid=25: File exists
May 13 14:35:34 tsgp1403 sendmail[15873]: [ID 801593 mail.alert] n4DHe0KO027983: queueup: cannot create ./tfn4DHe0KO027983, uid=25: File exists
May 13 14:35:35 tsgp1403 sendmail[15916]: [ID 801593 mail.alert] n4DHe0KO027983: queueup: cannot create ./tfn4DHe0KO027983, uid=25: File exists

Finally they realized that the permissions of /etc were set to 775. Once they changed it, sendmail started.

In a different article on oreillynet, I found the information that sendmail won't work properly if permissions are incorrect on any of these directories:

You have to check the permissions on / and all the subdirectories like /etc, /etc/mail for write permissions. If there is no write permission on / or /etc then give the write permissions and check.

This will set the permissions for every directory sendmail needs to be
non-group writable:

sudo chmod go-w / /etc /etc/mail /usr /var /var/spool /var/spool/mqueue /private

Check all these permissions are same as below.

drwxr-xr-x 45 root sys 3584 Feb 3 10:24 etc
drwxr-xr-x 2 root mail 512 Feb 3 11:54 mail
-rw-r--r-- 1 root bin 153 Sep 30 10:24 Mail.rc
-rw-r--r-- 1 root bin 1201 Sep 30 10:24 aliases
-rw-r--r-- 1 root mail 0 Oct 10 04:58 aliases.dir
-rw-r--r-- 1 root mail 1024 Oct 10 04:58 aliases.pag
-rw-r--r-- 1 root bin 5266 Sep 27 19:07 helpfile
-rw-r--r-- 1 root bin 0 Sep 24 2001 local-host-names
-rw-r--r-- 1 root bin 1829 Sep 30 10:19 mailx.rc
-r--r--r-- 1 root bin 34924 Sep 30 10:24 main.cf
-r--r--r-- 1 root bin 35625 Oct 1 05:09 sendmail.cf
-r--r--r-- 1 root other 35625 Oct 1 05:09
sendmail.cf.pre110615-05
lrwxrwxrwx 1 root root 8 Sep 30 10:24 sendmail.hf ->
helpfile
-r--r--r-- 1 root bin 35625 Sep 30 10:24 subsidiary.cf
-rw-r--r-- 1 root bin 5 Sep 24 2001 trusted-users