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.
Install the package .
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.
- 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
AuthPassline. Spaces in the password can be omitted.
- If you do not use two-factor authentication, you need to allow access to unsecure apps. You can do so on your Less Secure Apps page.
# 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 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. Must be correctly formed, fully qualified domain name or GMail will reject connection. hostname=yourlocalhost.yourlocaldomain.tld # Use SSL/TLS before starting negotiation UseTLS=Yes UseSTARTTLS=Yes # Username/Password AuthUser=username AuthPass=password AuthMethod=LOGIN # Email 'From header's can override the default domain? FromLineOverride=yes
Create aliases for local usernames (optional)
To test whether the Gmail server will properly forward your email:
$ echo -n 'Subject: test\n\nTesting ssmtp' | sendmail -v 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 myhost /etc/passwd
root:x:0:0:root at myhost,,,:/root:/bin/bash mainuser:x:1000:1000:mainuser at myhost,,,:/home/mainuser:/bin/bash
Because your email password is stored as cleartext in
/etc/ssmtp/ssmtp.conf, it is important that this file is secure. By default, the entire
/etc/ssmtp directory is accessible only by root and the mail group. The
/usr/bin/ssmtp binary runs as the mail group and can read this file. There is no reason to add yourself or other users to the mail group.
To send email from the terminal, do:
$ echo -e "Subject: this is the subject\n\nthis is the body" | mail firstname.lastname@example.org
or interactively as:
$ sendmail email@example.com Subject: this is my subject CC: firstname.lastname@example.org Now I can type the body here
don 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
To:email@example.com From:firstname.lastname@example.org Subject: Test This is a test mail.
$ sendmail -t < test-mail.txt
Some users might prefer the syntax of mail from, , or other mailx providers instead. For example, mail has options to provide the subject as an argument. mail requires sendmail and can use as sendmail.
Alternatively, you can attach using uuencode from. To attach 'file.txt' as 'myfile.txt':
$ uuencode file.txt myfile.txt | sendmail email@example.com
Mail to Local Users
Messages sent to local users (or any other address not ending in @fqdn are treated in one of two ways
- destination user has UID < 1000 - The address is replaced by the address defined by
- destination user has UID ≥ 1000 or the user is unknown - The the value from
/etc/ssmtp/ssmtp.confis appended to the end of the user id.
This can lead to problems if local users on your system aren't also valid users at your
rewriteDomain, but are receiving mail from system services, esp if your rewrite domain is a public service like
To work around this, you can use mail from
$ grep alias /etc/mail.rc
alias git git<firstname.lastname@example.org> alias archuser 'My Name'<email@example.com>
You can then pipe messages into mail instead of into sendmail.
$ echo -e "Hey archuser." | mail archuser
/bin/mail. Don't do this. sendmail and mail have different syntax for both arguments and standard input. It is better to find the processes that are using sendmail directly and configure them to use mail instead.