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Add information about how the new sendmail set-group-ID mail submission

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works and ways to work around common problems people might have.
Include information on reverting to a set-user-ID root sendmail binary in
case anyone really needs to do this.
This commit is contained in:
Gregory Neil Shapiro 2002-02-17 22:14:29 +00:00
parent a8247f3a53
commit 5cd5c25e71
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=90807
1 changed files with 39 additions and 0 deletions
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etc/mail/README
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# $FreeBSD$
Sendmail Processes
As of sendmail 8.12, in order to improve security, the sendmail binary no
longer needs to be set-user-ID root. Instead, a set-group-ID binary
accepts command line mail and relays it to a full mail transfer agent via
SMTP. A group writable client mail queue (/var/spool/client-mqueue/ by
default) holds the mail if an MTA can not be contacted.
To accomplish this, under the default setup, an MTA must be listening on
localhost port 25. If the rc.conf sendmail_enable option is set to false,
a sendmail daemon will still be started and bound only to the localhost
interface in order to accept command line submitted mail. If this is not
a desirable solution, it can be disabled using the sendmail_submit_enable
rc.conf option. However, if both sendmail_enable and sendmail_submit_enable
are turned off, you must do one of two things for command line submitted
mail:
1. Designate an alternative MTA for the submission agent to contact
by altering /etc/mail/submit.mc and using 'make submit.cf' in
/etc/mail/. Change the FEATURE(msp) line to FEATURE(msp, hostname)
where hostname is the fully qualified hostname of the alternative MTA.
Or:
2. Return to using a set-user-ID root sendmail binary by changing the
ownership and permissions on the sendmail binary and removing the
/etc/mail/submit.cf file::
chown root /usr/libexec/sendmail/sendmail
chmod 4755 /usr/libexec/sendmail/sendmail
rm /etc/mail/submit.cf
If you install from source, set the SENDMAIL_SET_USER_ID flag in
/etc/make.conf.
Also, as of 8.12, a new queue-running daemon is started to make sure mail
doesn't remain in the client mail queue. Be default, it simply runs the
client mail queue every 30 minutes. It's behavior can be adjusted by setting
the sendmail_msp_queue_enable and sendmail_msp_queue_flags rc.conf options.
Filtering out SPAM from your site
Sendmail now includes excellent tools to block spam. These tools are