SSMTP - ArchWiki

# SSMTP

SSMTP is a program which delivers email from a local computer to a configured mailhost (mailhub). It is not a mail server (like feature-rich mail server sendmail) and does not receive mail, expand aliases or manage a queue. One of its primary uses is for forwarding automated email (like system alerts) off your machine and to an external email address.

## Installation

Install the package ssmtp.

## Forward to a Gmail mail server

To configure SSMTP, you will have to edit its configuration file (`/etc/ssmtp/ssmtp.conf`) and enter your account settings:

    /etc/ssmtp/ssmtp.conf

    # The user that gets all the mails (UID < 1000, usually the admin)
    root=username@gmail.com

    # The mail server (where the mail is sent to), both port 465 or 587 should be acceptable
    # See also https://support.google.com/mail/answer/78799
    mailhub=smtp.gmail.com:587

    # The address where the mail appears to come from for user authentication.
    rewriteDomain=gmail.com

    # The full hostname
    hostname=localhost

    # Use SSL/TLS before starting negotiation
    UseTLS=Yes
    UseSTARTTLS=Yes

    # Username/Password
    AuthUser=username
    AuthPass=password

    # Email 'From header's can override the default domain?
    FromLineOverride=yes

Note: Take note, that the shown configuration is an example for Gmail, You may have to use other settings. If it is not working as expected read the man page `man 8 ssmtp`, please.

Create aliases for local usernames (optional)

    /etc/ssmtp/revaliases

    root:username@gmail.com:smtp.gmail.com:587
    mainuser:username@gmail.com:smtp.gmail.com:587

To test whether the Gmail server will properly forward your email:

    $ echo test | mail -v -s "testing ssmtp setup" tousername@somedomain.com

Note:

The factual accuracy of this article or section is disputed.

Reason: "Recently"? [1] and [2]. (Discuss in Talk:SSMTP#)
Gmail has recently started blocking emails from senders that do not authenticate using OAuth. To allow SSMTP to use gmail's SMTP server, you need to allow access to unsecure apps.

Change the 'From' text by editing `/etc/passwd` to receive mail from 'root at myhost' instead of just 'root'.

    # chfn -f 'root at myhost' root
    # chfn -f 'mainuser at myhost' mainuser

Which changes `/etc/passwd` to:

    $ grep myhostname /etc/passwd

    root:x:0:0:root@myhostname,,,:/root:/bin/bash
    mainuser:x:1000:1000:mainuser@myhostname,,,:/home/mainuser:/bin/bash

### Using an app password

If your Gmail account is secured with two-factor authentication, you need to generate a unique App Password to use in `ssmtp.conf`. You can do so on your App Passwords page. Use the generated 16-character password in the `AuthPass` line. Spaces in the password can be omitted.

## Security

Because your email password is stored as cleartext in `/etc/ssmtp/ssmtp.conf`, it is important to secure the file. Securing ssmtp.conf will ensure that:

- if any users have unprivileged access to your system, they cannot read the file and see your email password, while still letting them send out email
- if your user account is ever compromised, the hacker cannot read the `ssmtp.conf` file, and therefore your email password, unless he gains access to the root account as well

To secure `ssmtp.conf`, do this:

Create an `ssmtp` group:

    # groupadd ssmtp

Set ssmtp.conf group owner to the new `ssmtp` group:

    # chown :ssmtp /etc/ssmtp/ssmtp.conf

Set the group owner of the ssmtp binary to the new `ssmtp` group:

    # chown :ssmtp /usr/bin/ssmtp

Make sure only root, and the `ssmtp` group can access `ssmtp.conf`:

    # chmod 640 /etc/ssmtp/ssmtp.conf

Set the SGID bit on the ssmtp binary.

    # chmod g+s /usr/bin/ssmtp

Now, all the regular users can still send email using the terminal, but none can read the `ssmtp.conf` file.

## Sending email

To send email from the terminal, do:

    $ echo "this is the body" | mail -s "Subject" username@somedomain.com

or interactively as:

    $ mail username@somedomain.com

Note: When using mail interactively, after typing the Subject and hitting enter, you type the body. Hit `Ctrl`+`d` on a blank line to end your message and automatically send it out.

An alternate method for sending emails is to create a text file and send it with ssmtp or mail

    test-mail.txt

    To:username@somedomain.com
    From:youraccount@gmail.com
    Subject: Test

    This is a test mail.

Send the `test-mail.txt` file

    $ mail username@somedomain.com < test-mail.txt

### Attachments

If you need to be able to add attachments, install and configure Mutt and Msmtp and then go see the tip at nixcraft.

Alternatively, you can attach using uuencode:

    $ uuencode file.txt file.txt | mail user@domain.com

## References

- SSMTP and Gmail on the Arch forums
- Sending Email From Your System with sSMTP
- The Qnd Guide to ssmtp
- GMail Support - Configuring other mail clients

Category:

- Mail server

Hidden category:

- Pages or sections flagged with Template:Accuracy