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If you update your configuration from 8.11.x you need to install an
additional config file: /etc/mail/submit.cf, you can generate it
by calling the target 'submit.cf', submit.mc will be installed too.
/usr/ports/mail/sendmail$ make submit.cf

you should add in /etc/make.conf:
SENDMAIL_CF_DIR=	%%PREFIX%%/share/sendmail/cf

To activate only the delivery from the local submission queue see:
%%PREFIX%%/etc/rc.d/sm-client.sh.sample

To activate all sendmail processes see:
%%PREFIX%%/etc/rc.d/sendmail.sh.sample

To deliver all local mail to your mailhub, edit the last line of submit.mc:
FEATURE(`msp','[mailhub.do.main]`)dnl

in FreeBSD-RELEASE < 4.6 set your flags in /etc/rc.conf:
sendmail_flags="-L sm-msp-queue -Ac -q1m"

To update your configuration look at %%PREFIX%%/share/sendmail/cf/README.
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To activate sendmail as your default mailer, call the target 'mailer.conf':
/usr/ports/mail/sendmail$ make mailer.conf

Your '/etc/mail/mailer.conf' should look like this:
#
# Execute the "real" sendmail program, named /usr/libexec/sendmail/sendmail
#
sendmail	%%PREFIX%%/sbin/sendmail
send-mail	%%PREFIX%%/sbin/sendmail
mailq		%%PREFIX%%/sbin/sendmail
newaliases	%%PREFIX%%/sbin/sendmail
hoststat	%%PREFIX%%/sbin/sendmail
purgestat	%%PREFIX%%/sbin/sendmail

You may also need to update /etc/rc.conf.
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