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:

    # 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 http://mail.google.com/support/bin/answer.py?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

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

## 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