Ubuntu16.04 build postfix as SMTP server

First, DNS configuration

Type	name	value	TTL
A	Mail	128.199.254.32	1 hours
Mx	@	mail.example.com ( priority:Ten)	1 hours
Txt	@	v=spf1 mx:mail.example.com ip4:128.199.254.32 ~all	1 hours
TXT	Mail._domain	KeyV=dkim1;k=rsa; P=migfma0gcsqgsi ...	1 hours

Where you can configure A and MX records first,

Two txt records are used for "anti-spam ", where Dkim requires a native configuration, which is described in detail later in this article.

Second, Postfix Installation and Configuration

2.1 set it up beforehand. hostname ,Postfix can automatically configure a lot of parameters, save time.

Echo "example.com" >/etc/hostname

2.2 Installing postfix

Install mailutils

The default option is Internet Site , fill example.com Press ENTER.

2.3 Basic Configuration

Modify a file /etc/postfix/main.cf

= = = = Loopback-only

Then restart the service.

# systemctl Restart Postfix

2.4 now can send e-mail, test to see if you can receive.

Echo "Body of the email" | Mail-s "Subject line" your_email_address

2.5 (optional configuration) to use TLS encryption

third, anti-spam settings: SPF ,DKIM and DMARC

3.1 SPF just add DNS Records, here 's the point. DKIM installation configuration

Install Opendkim opendkim-tools

3.2 Edit File/etc/opendkim.conf append the following configuration to the bottom of the file:autorestart Yesautorestartrate Ten/1h

UMask002Syslog yessyslogsuccess yeslogwhy yescanonicalization relaxed/simpleexternalignorelist refile:/etc/opendkim/trustedhostsinternalhosts refile:/etc/opendkim/trustedhostskeytable refile:/etc/opendkim/keytablesigningtable refile:/etc/opendkim/Signingtablemode Svpidfile/var/run/opendkim/opendkim.pidsignaturealgorithm RSA-sha256
UserID opendkim:opendkimsocket inet:12301@localhost

3.3 Edit/etc/default/opendkim, comment out the original socket configuration, add new configuration:

socket="inet:[email protected]"

3.4 Edit/etc/postfix/main.cf, Add the following configuration:

6 milter_default_action = Accept

Among them, when the postfix version is 2.6+, milter_protocol=6; The version is 2.3 to 2.5, milter_protocol=2;

View Postfix version information:

grep mail_version

If you already have smtpd_milters and non_smtpd_milters configurations, append the following:

Smtpd_milters = Unix:/spamass/spamass.sock, inet:localhost:12301 non_smtpd_milters = unix:/spamass/ Spamass.sock, Inet:localhost:12301

If there is no related configuration, use it directly:

Smtpd_milters = inet:localhost:12301 non_smtpd_milters = inet:localhost:12301

3.5 Execute the following command

sudo mkdir sudo mkdir /etc/opendkim/keys

3.6 Create/etc/opendkim/trustedhosts, the first three lines do not change

127.0. 0.1 localhost 192.168. 0.1/ *.example.com

3.7 Create /etc/opendkim/keytable

Mail._domainkey.example.com example.com:mail:/etc/opendkim/keys/example.com/mail.private

3.8 Create /etc/opendkim/signingtable

* @example. com mail._domainkey.example.com

3.9 Execute the following command:

sudo mkdir  sudo opendkim-genkey-sudochown Opendkim:opendkim Mail.private

3.10 Next, create a DNS TXT record:

which , name is mail._domainkey

Value to refer to/etc/opendkim/keys/example.com/mail.txt, in the format:

V=DKIM1; K=rsa; P=migfma0gcsqgsib3dqebaquaa4gnadcbiqkbgqc5n3lnvvrygpcrsoqn+awtpe+ Igyckbppo8hhbcffciiv10hwo4phcogzsakvhojdm4yefkxhqjm7ikzepubate7o47hax1cjpnuidlxhilsbembmxjrjag0hzvn8z6eaoohznaphmk2h4uurj Og8za5bhfzjf7tgwi+k619ffuwidaqab

3.11 Restart the service.

sudo sudo service opendkim restart

If you have errors, check the logs:/var/log/mail.err and/var/log/mail.log

Reference Documentation:

[1]" How to install and configure Postfix on Ubuntu 16.04 as only sending SMTP server ",/ HTTP/ blog.csdn.net/zstack_org/article/details/69525954

[2]"Email Basics SPF Setting Description ", https://tieba.baidu.com/p/3166555301?red_tag= 1967972912

[3]" support for message encryption with SSL Postfix+ssl configuration ", http://shellyli.iteye.com/blog/1534717

Ubuntu16.04 build postfix as SMTP server