Terminology

DKIM

DomainKeys Identified Mail: a system for digitally signing email that provides the means to securely verify that the email's origin is legitimate.

DNS

wikipedia:Domain Name System: a naming system for computers, services, or any resource connected to the Internet or a private network (i.e. that identifies "google.com" with its internet protocol address)

FQDN

wikipedia:Fully qualified domain name: a domain name that specifies its exact location in the tree hierarchy of the Domain Name System (DNS).

MTA

wikipedia:Message transfer agent: an email relay service, i.e. Postfix, QMail or Exim4.

SMTP

wikipedia:Simple Mail Transfer Protocol: a network protocol for sending email to a remote server, often involving password authentication and end-to-end SSL encryption.

SSL

(a.k.a Transport Layer Security) a method of connecting to a remote network host that encrypts traffic on any given network protocol that uses it.

TLS

wikipedia:Transport Layer Security a method of connecting to a remote network host that encrypts traffic on any given network protocol that uses it.

cron

wikipedia:Cron: a job scheduler for UNIX-like operating systems

installation directory

The directory (folder) on the web server where X2Engine is installed. You will know that you are operating within this directory when you see a file constants.php and the following subdirectories: assets, css, custom, framework, images, js, protected, themes and uploads.

user menu

The menu accessed by clicking on one's own username in the far upper-right-hand corner of the application.