1 2 Sendmail Processes 3 4 As of sendmail 8.12, in order to improve security, the sendmail binary no 5 longer needs to be set-user-ID root. Instead, a set-group-ID binary 6 accepts command line mail and relays it to a full mail transfer agent via 7 SMTP. A group writable client mail queue (/var/spool/clientmqueue/ by 8 default) holds the mail if an MTA can not be contacted. 9 10 To accomplish this, under the default setup, an MTA must be listening on 11 localhost port 25. If the rc.conf sendmail_enable option is set to "NO", 12 a sendmail daemon will still be started and bound only to the localhost 13 interface in order to accept command line submitted mail (note that this 14 does not work inside jail(2) systems as jails do not allow binding to 15 just the localhost interface). If this is not a desirable solution, it 16 can be disabled using the sendmail_submit_enable rc.conf option. However, 17 if both sendmail_enable and sendmail_submit_enable are set to "NO", you 18 must do one of two things for command line submitted mail: 19 20 1. Designate an alternative host for the submission agent to contact 21 by altering /etc/mail/freebsd.submit.mc (or setting SENDMAIL_SUBMIT_MC 22 in /etc/make.conf to an alternate .mc file) and using 23 'make install-submit-cf' in /etc/mail/. Change the FEATURE(msp) line 24 to FEATURE(msp, hostname) where hostname is the fully qualified hostname 25 of the alternative host. 26 27 Or: 28 29 2. Return to using a set-user-ID root sendmail binary by changing the 30 ownership and permissions on the sendmail binary and removing the 31 /etc/mail/submit.cf file: 32 chown root /usr/libexec/sendmail/sendmail 33 chmod 4755 /usr/libexec/sendmail/sendmail 34 rm /etc/mail/submit.cf 35 If you install from source, set the SENDMAIL_SET_USER_ID flag in 36 /etc/make.conf. 37 38 Also, as of 8.12, a new queue-running daemon is started to make sure mail 39 doesn't remain in the client mail queue. By default, it simply runs the 40 client mail queue every 30 minutes. Its behavior can be adjusted by setting 41 the sendmail_msp_queue_enable and sendmail_msp_queue_flags rc.conf options. 42 43 44 Filtering out SPAM from your site 45 46 Sendmail now includes excellent tools to block spam. These tools are 47 available as FEATUREs that you can add to your site's .mc file. Proper use 48 of these FEATUREs will prevent spammer from using your site as a relay as 49 well as significantly decrease the amount of spam that arrives at your 50 site. No set of anti-spam tools will block all spam without blocking some 51 portion of legitimate mail as well. Therefore, these FEATUREs are designed 52 to prevent as much spam as possible without blocking legitimate mail. 53 54 These tools are discussed in /usr/share/sendmail/cf/README. Read the 55 section entitled "ANTI-SPAM CONFIGURATION CONTROL". Example usage and 56 additional tools can be found in /usr/share/sendmail/cf/cf/knecht.mc. 57 58