Get DKIM Working with OpenSMTPD
Anything is easy (in hindsight)
debian
Linux Commands Tips and Tricks
You can’t forget that which you put on your blog
Get an Email When Your Server Needs Updating
apticron to the rescue
Interesting UNIX, BSD, Linux programs and Packages
A Post-it™ note for *nix stuff.
OpenSMTPD for Outgoing Mail Only
Sending email should be easy