This guide assumes you have a working Postfix server and want it to sign with DKIM. There are a few things we have to understand to make all of this work though, which require you to be familiar with DNS as well. 1.) Install OpenDKIM apt install opendkim systemctl enable opendkim 2.) Edit /etc/opendkim.conf Syslog yes SyslogSuccess yes Mode&nbs........

This just simply outputs what you need a username and password that can be used to authenticate from .htaccess htpasswd -nb user password user:Gnb6uE9Lp4gt2 If you want to write it straight to a file htpasswd -cb /tmp/somefile.pw user password How To Use This In .htaccess AuthUserFile /tmp/somefile.pw AuthName GetLost!! AuthType B........

This can be very tricky, say you are doing development on a file that is symlinked. Doing a "cp dev.file dev.file-bk" won't do what you expect, it just links back to the same file so you haven't copied or backed anything up. You need the "-H" switch to copy the actual file that is referenced by the symlink: cp -Hdev.file dev.file-bk........