Ubuntu – Sending Mail from Command Line Automatically

Why does it have to be postfix directly? mailx -a, mutt, or mutt -a will also use the sendmail interface -- unless you configure them for SMTP.

echo "This is a test message" | mutt -s Test -a foo.zip -- $USER

echo "This is a test message" | mail -s Test -a foo.zip $USER

(Note, in bsd-mailx the option is -A instead.)

Anyway, here's a "postfix" example.

Replace $USER, content type and filename to match your environment. Example assumes you are sending the message to yourself and have a ZIP file foo.zip in the current directory.

(printf "%s\n" \
    "Subject: test" \
    "To: $USER" \
    "Content-Type: application/zip" \
    "Content-Disposition: attachment; filename=foo.zip" \
    "Content-Transfer-Encoding: base64" \
    "";
 base64 foo.zip) | sendmail "$USER"

(Creation of MIME multipart messages left as an exercise to the reader.)

You do need a special SMTP server, but you don't need to set it up yourself. As somebody has already suggested, you can create a bogus Gmail account and use the SMTP for that. Or, for really anonymity, you can use a SMTP provider; this will allow you to forge your return address (the same way spammers do) for an extra layer of anonymity and customization ("From: YourFriend@SecretSanta.com").

Here's help on configuring sendmail to use SMTP, useful when specifying headers directly instead of relying on your mail client.