This littler wrapper script is intended to rewrite all mails to user specified from address. In addition a central address is provided where all mails for local users go to. This prevents that mails that are intented for you/root go to the wrong person, but instead to your defined email address.
Without rewriting the from address to that of your mailaccount your local username and hostname is exposed to the receiver, like X-Google-Original-From: <root@raspberrypi>
With rewriting E-Mail will appear as truly send from like MailSenderUser1234@gmail.com
Please also set /etc/nullmailer/idhost to something like nullhost otherwise your hostname will be exposed in Message-ID header-field.
Please also set /etc/nullmailer/helohost to something like nullhost otherwise your hostname will be exposed in Received: from header.
Execute as root (if applicable change the paths):
cd /usr/sbin
mv sendmail sendmail-bin
copy sendmail from this repository to /usr/sbin/sendmail edit the copied sendmail file at these lines:
export NULLMAILER_USER=yourmailaddress e.g. MailSenderUser1234
export NULLMAILER_HOST=yourMailDomain e.g. gmail.com
Admin_Address=yourMailAdress@yourMailDomain.com Where should mails go that are directed for local users like "root" or "pi" e.g. MailSenderUser1234@gmail.com or alertqueue@example.net This address is idependent of sender address
chmod --reference=sendmail-bin sendmail to prevent normal users to make changes and intercept all mail from this host
Please set
/etc/nullmailer/adminaddr to your admin-address. If some program sends to "@" e.g. "root@mysuperhost" or "blabla@localhost" this address is rewritten by nullmailer.
If it is only send to "root" or "pi" like some programs do, then it is rewritten by this script. For maximum complexity disregarding KISS principle these both addresses could differ.