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.
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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) firstname.lastname@example.org # 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
man 8 ssmtp, please.
Create aliases for local usernames (optional)
To test whether the Gmail server will properly forward your email:
echo test | mail -v -s "testing ssmtp setup" email@example.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
grep myhostname /etc/passwd
An alternate method for sending emails is to create a text file and send it with 'ssmtp' or 'mail'
To:firstname.lastname@example.org From:email@example.com Subject: Test This is a test mail.
mail firstname.lastname@example.org < test-mail.txt
Alternatively, you can attach using uuencode
uuencode file.txt file.txt | mail email@example.com
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:
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.