Postfix is an alternative to the widely used Sendmail Message Transfer Agent (MTA). For information about Postfix, go to http://www.postfix.org. The procedures in this topic will work with Linux, macOS, or Unix.

Prerequisites

Before you complete the procedures in this section, you must perform the following tasks:

Configuring Postfix

Complete the following procedures to configure your mail server to send email through Amazon SES using Postfix.

To configure Postfix

1. In a text editor, open the file /etc/postfix/main.cf.
2. Add the following lines to the end of main.cf:
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   relayhost = [email-smtp.us-west-2.amazonaws.com]:587 smtp_sasl_auth_enable = yes smtp_sasl_security_options = noanonymous smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd smtp_use_tls = yes smtp_tls_security_level = encrypt smtp_tls_note_starttls_offer = yes

   Note

   If you use Amazon SES in an AWS Region other than US West (Oregon), replace email-smtp.us-west-2.amazonaws.com in the example above with the SMTP endpoint of the appropriate region. For more information, see Regions and Amazon SES.

3. In a text editor, open the file /etc/postfix/master.cf.
4. In master.cf, locate the following line:

   -o smtp_fallback_relay=

   Place a # (hash) character at the beginning of the line to comment it out. Save and close master.cf.

5. In a text editor, open the file /etc/postfix/sasl_passwd. If the file does not already exist, create it.
6. Add the following line to sasl_passwd:
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   [email-smtp.us-west-2.amazonaws.com]:587 SMTPUSERNAME:SMTPPASSWORD

   Note

   Replace SMTPUSERNAME and SMTPPASSWORD with your SMTP username and password, respectively. Your SMTP user name and password are not the same as your AWS access key ID and secret access key. For more information about credentials, see Obtaining Your Amazon SES SMTP Credentials.

   If you use Amazon SES in an AWS Region other than US West (Oregon), replace email-smtp.us-west-2.amazonaws.com in the example above with the SMTP endpoint of the appropriate region. For more information, see Regions and Amazon SES.

   Save and close sasl_passwd.

7. At a command prompt, type the following command to create a hashmap database file containing your SMTP credentials: sudo postmap hash:/etc/postfix/sasl_passwd
8. (Optional) The /etc/postfix/sasl_passwd and /etc/postfix/sasl_passwd.db files you created in the previous steps are not encrypted. Because these files contain your SMTP credentials, we recommend that you modify the files’ ownership and permissions in order to restrict access to them. To restrict access to these files:
   1. At a command prompt, type the following command to change the ownership of the files: sudo chown root:root /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
   2. At a command prompt, type the following command to change the permissions of the files so that only the root user can read or write to them: sudo chmod 0600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
9. Tell Postfix where to find the CA certificate (needed to verify the Amazon SES server certificate). The command you use in this step varies based on your operating system.
   • If you use Amazon Linux, Red Hat Enterprise Linux, or a related distribution, type the following command: sudo postconf -e ‘smtp_tls_CAfile = /etc/ssl/certs/ca-bundle.crt’
   • If you use Ubuntu or a related distribution, type the following command: sudo postconf -e ‘smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt’
10. Type the following command to start the Postfix server (or to reload the configuration settings if the server is already running): sudo postfix start; sudo postfix reload
11. Send a test email by typing the following at a command line, pressing Enter after each line. Replace sender@example.com with your From email address. The From address must be verified for use with Amazon SES. Replace recipient@example.com with the destination address. If your account is still in the sandbox, the recipient address must also be verified. Finally, the final line must contain a single period (.) with no other content.
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    sendmail -f sender@example.com recipient@example.com From: Sender Name <sender@example.com> Subject: Amazon SES Test This message was sent using Amazon SES. .

    Note

    In some versions of Ubuntu, when you enter the sendmail -f command, you may see the following error message: command not found: sendmail. In this situation, replace sendmail in the command above with /usr/lib/sendmail.

12. Check the mailbox associated with the recipient address. If the email does not arrive, check your junk mail folder. If you still cannot locate the email, check your system’s mail log (typically located at/var/log/maillog) for more information.

Advanced Usage Example

This example shows how to send an email that uses a configuration set, and that uses MIME-multipart encoding to send both a plain text and an HTML version of the message, along with an attachment. It also includes a link tag, which can be used for categorizing click events. The content of the email is specified in an external file, so that you do not have to manually type the commands in the Postfix session.

To send a multipart MIME email using Postfix

1. In a text editor, create a new file called mime-email.txt.
2. In the text file, paste the following content, replacing the values in red with the appropriate values for your account:
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   X-SES-CONFIGURATION-SET:ConfigSet From:Sender Name <sender@example.com> Subject:Amazon SES Test MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="YWVhZDFlY2QzMGQ2N2U0YTZmODU" --YWVhZDFlY2QzMGQ2N2U0YTZmODU Content-Type: multipart/alternative; boundary="3NjM0N2QwMTE4MWQ0ZTg2NTYxZQ" --3NjM0N2QwMTE4MWQ0ZTg2NTYxZQ Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Amazon SES Test This message was sent from Amazon SES using the SMTP interface. For more information, see: http://docs.aws.amazon.com/ses/latest/DeveloperGuide/send-email-smtp.html --3NjM0N2QwMTE4MWQ0ZTg2NTYxZQ Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable <html> <head> </head> <body> <h1>Amazon SES Test</h1> <p>This message was sent from Amazon SES using the SMTP interface.</p> <p>For more information, see <a ses:tags="samplekey0:samplevalue0;samplekey1:samplevalue1;" href="http://docs.aws.amazon.com/ses/latest/DeveloperGuide/send-email-smtp.html"> Using the Amazon SES SMTP Interface to Send Email</a> in the <em>Amazon SES Developer Guide</em>.</p> </body> </html> --3NjM0N2QwMTE4MWQ0ZTg2NTYxZQ-- --YWVhZDFlY2QzMGQ2N2U0YTZmODU Content-Type: application/octet-stream MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="customers.txt" SUQsRmlyc3ROYW1lLExhc3ROYW1lLENvdW50cnkKMzQ4LEpvaG4sU3RpbGVzLENh bmFkYQo5MjM4OSxKaWUsTGl1LENoaW5hCjczNCxTaGlybGV5LFJvZHJpZ3VleixV bml0ZWQgU3RhdGVzCjI4OTMsQW5heWEsSXllbmdhcixJbmRpYQ== --YWVhZDFlY2QzMGQ2N2U0YTZmODU--

   Save and close the file.

3. At the command line, type the following command: sendmail recipient@example.com < mime-email.txt

   If the command runs successfully, it exits without providing any output.

4. Check your inbox for the email. If the message was not delivered, check your system’s mail log.