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Configure email sending via sSMTP on Linux

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For your information

This guide explains how to configure email campaigns using the Selectel mail service via the sSMTP utility on a Linux server.

  1. Ensure that you have connected a mail service for the domain and that the domain has the status Verified. You can view connected domains and their statuses in the control panel: in the top menu, click Products → Mail Service → resource page → Information tab → Linked domains block.

  2. Connect to the server in the Selectel infrastructure from which you plan to send emails:

    Connect to the server via SSH or via KVM console.

  3. Install sSMTP:

    sudo apt update
    sudo apt install ssmtp

  4. Install the mailx utility to send emails:

    sudo apt install mailutils

  5. Install nano:

    sudo apt install nano

  6. Open the ssmtp.conf configuration file:

    nano /etc/ssmtp/ssmtp.conf

  7. Edit the file content:

    mailhub=smtp.mail.selcloud.ru:<port>
    AuthUser=<login>
    AuthPass=<password>
    AuthMethod=LOGIN
    rewriteDomain=<example.com>
    hostname=smtp.mail.selcloud.ru
    FromLineOverride=No
    UseSTARTTLS=Yes
    UseTLS=Yes
    # If <port>=1126, then UseTLS=No
    TLS_CA_File=/etc/ssl/certs/ca-certificates.crt

    Specify:

    • <port> — port:

      • 1126 — if you need to establish a non-SSL / STARTTLS connection; ;
      • 1127 — if you need to establish a TLS (SSL) connection.

    • <login> — login, which can be found in the control panel: in the top menu, click Products → Mail Service → resource page to which the domain is added → Information tab;

    • <password> — password, which can be found in the control panel: in the top menu, click Products → Mail Service → resource page to which the domain is added → Information tab;

    • <example.com> — the domain you want to send emails from.

  8. Close the file ( **Ctrl+X **) and save the changes ( **Y **). .

  9. Open the revaliases configuration file:

    sudo nano /etc/ssmtp/revaliases

  10. Add a line with the address that should be displayed as the sender address in email campaigns via the mail service:

    root:<sender_email>:smtp.mail.selcloud.ru:<port>

    Specify:

    • <sender_email> — the sender address on the domain you connected to the mail service, for example sender@example.com;
    • <port> — the port you specified in step 7.

  11. Close the file ( **Ctrl+X **) and save the changes ( **Y **). .

  12. Replace the default mail sender with the configured sSMTP:

    sudo mv /usr/sbin/sendmail /usr/sbin/sendmail.orig

  13. Create a symlink to ssmtp instead of sendmail:

    sudo ln -s /usr/sbin/ssmtp /usr/sbin/sendmail

  14. Send a test email:

    $ echo test | mail -s "testing ssmtp" <recipient_email>

    Specify <recipient_email> — the address you want to send the test email campaign to.