MessageLabs FAQ - General Terminology

An MX record is a type of resource record in the Domain Name System (DNS) that defines how email is routed. MX records point to the servers that should receive email and define their priority relative to each other. Your MX records route your inbound email via the MessageLabs infrastructure, where the email is scanned by the Email Services and before being routed on to your email recipients.

To direct your email via the MessageLabs infrastructure, your MX records must be amended to ensure that all your email is scanned. MX records are the DNS (Domain Name Server) settings for your domains. They are used as pointers to the location that your email addresses are delivered to.

First, identify who is hosting your domain/s; that is, the person or organisation that is responsible for maintaining your organisation’s MX records or DNS Settings. This may be your Internet Service Provider (ISP). Typically, each provider will supply an online form to make any changes, or you may have to email or call them to notify them that you will require a change of your MX records.

If you're receiving the "553 Sorry that domain isn't allowed to be relayed through this host" error, then that means that SMTP authentication has not been enabled in your email program. You'll need to enable SMTP authentication in order to be able to send emails.

The Domain Name System (DNS) helps users to find their way around the Internet. Every computer on the Internet has a unique address (like a telephone number) consisting of a difficult-to-remember string of numbers (also known as an "IP address"). DNS allows a familiar string of letters (the "domain name") to be used instead of IP addresses, making the process of finding and remembering a web site's location easier. Translating a domain name into an IP address is referred to as "resolving" the domain names.

Bandwidth is the amount of data that can be sent through a connection. With regards to a hosting account, bandwidth is used interchangeably with the term "data transfer" to measure the amount of data your account is allowed to transfer in a given time period (usually per month).

HTTP (HyperText Transfer Protocol) is the standard Internet protocol for the exchange of information on the World Wide Web. Basically, it defines how messages are formatted and transmitted, and what actions web servers and browsers should take in response to various commands. For example, when you enter a URL in your browser, this actually sends an HTTP command to the web server directing it to fetch and transmit the requested web page.

Https is the protocol for the server software that provides "secure" transactions on the World Wide Web. If a web site is running on an HTTPS server, you will see HTTPS instead of HTTP in the address bar of your browser. This verifies that you are in "secure mode."

An SSL certificate is used for the server authentication, data encryption, and message integrity checks. With a valid SSL certificate, your Internet communications are transmitted in encrypted form. Information you send can be trusted to arrive privately and unaltered to the server you specify (and no other).

A firewall is a safeguard utilised by many Local Area Networks (LANs) or Wide Area Networks (WANs) to protect the network from unauthorised access from the outside. They are basically gates that verify the users before they leave or enter the network by way of a User ID, Password or IP address.

This is the practice of distributing data across a network of servers in order to ensure that a single Web server does not get overloaded with work, thereby affecting performance or even causing the server to crash.

A virtual private network (VPN) is a private data network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling protocol and security procedures. The idea of the VPN is to give the company the same capabilities at much lower cost by using the shared public infrastructure rather than a private one.

IP stands for Internet Protocol Address. This is a unique number identifying all devices connected to the Internet. This number is usually shown in groups of numbers from 0 to 255, separated by periods, for example 207.46.230.218.

Attachments and emails are compared against a selected list of MIME types/subtypes, for example. application, audio, image, message, text, video, application, audio/wav, and video/mpeg. Email Content Control does not validate or check the accuracy of types/subtypes entered. No default lists are provided, although they can easily found by using internet search engines.

This is 'Simple Mail Transfer Protocol'. It's the protocol used to transfer email between computers. To direct your outbound email via the security services, you must make some configuration changes to your sending mail servers (SMTP servers).

Lightweight Directory Access Protocol (LDAP), the primary access protocol for Active Directory. LDAP is an industry-standard protocol that allows users to query and update information in a directory service. Active Directory supports both LDAP version 2 and LDAP version 3.

Secure Sockets Layer. A protocol that ensures the safety of data sent via the Internet.

MessageLabs servers return full details outlining why an email could not be delivered. If you receive a message with little or no detail it is because your client side server has stripped/blocked the MessageLabs response from the message.