Table of Contents

Sendmail Protocol

HELO {fromdomain}
MAIL FROM: {mailfrom}
RCPT TO: {mailto}
DATA
Subject:{subject}
{2x CR's}
{body}
.

QUIT

Sendmail Management

Connecting sendmail to a relay

In sendmail.mc, ass these lines 

define(`SMART_HOST', `smtp.server.com')dnl
...
MASQUERADE_AS(send.from.domain.com)
FEATURE(masquerade_envelope)

Authentication

Generate some certificates 

mkdir -p /etc/mail/ssl/ && cd /etc/mail/ssl
openssl req -new -x509 -keyout cakey.pem -out cacert.pem -days 3650
openssl req -nodes -new -x509 -keyout sendmail.pem -out sendmail.pem -days 3650
chmod 600 *

Add the authentication to access (Sendmail 8.12+) 

echo "AuthInfo:<smtp.server.com> \"U:root\" \"I:<username>\" \"P:<password>\" >> /etc/mail/access
makemap -r hash -t hash /etc/mail/access.db < access

Change lines in /etc/mail/sendmail.mc 

FEATURE(`authinfo',`hash /etc/mail/auth/auth.db')dnl
define(`SMART_HOST',`<smtp.server.com')dnl

define(`CERT_DIR', `/etc/mail/certs')
define(`confCACERT_PATH', `CERT_DIR')
define(`confCACERT', `CERT_DIR/ca-bundle.crt')
define(`confCRL', `CERT_DIR/ca-bundle.crt')
define(`confSERVER_CERT', `CERT_DIR/sendmail.pem')
define(`confSERVER_KEY', `CERT_DIR/sendmail.pem')
define(`confCLIENT_CERT', `CERT_DIR/sendmail.pem')
define(`confCLIENT_KEY'’, `CERT_DIR/sendmail.pem')

define(`confAUTH_MECHANISMS’, `EXTERNAL GSSAPI DIGEST-MD5 CRAM-MD5 LOGIN PLAIN’)

And regen the conf 

m4 sendmail.mc > sendmail.cf

SMTP by Domain Name

This will overwrite the smart_host parameter. This allows mail with different domains to be sent via different smtp servers 

root@aucsdcsrv0111 /u3/faxlink> cat /etc/mail/mailertable
pulsemining.com.au      smtp:smtp.auc.xstrata.int
xstratacoal.com.au      smtp:smtp.auc.xstrata.int