1.5 Ways to Protect Email

Why 1.5? Why not just 1 or 2? Well, just saying 1 isn't very interesting and, technically, this isn't actually 2 entirely different ways of doing it. So, without further adieu, here's the meat of the article.

First, some definitions. Throughout this article, you'll see mention of a good bit of alphabet soup. Some of the ones that you'll likely hear a lot of are DNS (Domain Name Service / Server), MX (the Mail Exchanger record in DNS), POP3 (the third generation of the Post Office Protocol) and IMAP4 (the fourth generation of Internet Message Access Protocol). So, before just delving in, I think it would be a good idea to make sure that everyone's on the same footing.

DNS - Domain Name Service. This is kindof a phone book for the Internet. When you type in www.cybertechcafe.net into your web browser, your computer will query it's DNS servers to learn that www.cybertechcafe.net actually points to 72.51.44.45. These DNS servers also provide other information about your domain name like where to send email to.

MX - You'll often hear this as an MX record, and it simply means the server that's responsible for receiving email for your domain. Any Internet domain name can have 0 or more MX records. If there is no MX record, the sending SMTP server will attempt to deliver it to the / an A record for the domain (that's another discussion). If there is 1 MX record for the domain, the sending mail server will attempt to deliver mail to that MX record and, if unsuccessful for a period of time (a configuration option on that server), will fail with an NDR or Non Delivery Report. If there are multiple MX records specified for the domain, each MX record will be assigned a 'metric' or 'priority'. The sending mail server will try each of the MX records listed until it either finds one that will accept the message or runs out (at which point it will fail and generate the NDR).

POP3 - This is a protocol that allows you to connect with email clients like MS Outlook, Mac Mail, Mozilla Thunderbird, etc., and download your email. The thing to remember about POP3 is that it downloads the messages from the mail server to your mail client so, by default, there is no copy left on the mail server. This is adequate in most residential environments, but typically is undesirable in a business or professional environment. Most POP3 clients can be configured to leave a copy of messages on the server, but this can quickly become a management nightmare.

IMAP4 - This is, in my opinion, an improvement over the POP3 protocol. Basically, all of the mail is stored on the [IMAP] server and summary information is sent to the email client. If the user creates folders on the client, those folders (and their contents) are replicated on the server. The advantage here is that email can be checked / viewed from multiple locations, and you can be certain that you're always seeing the up-to-date copy. Additionally, sent items are also stored on the server.

Now that we're all up to speed on the terminology, let's talk about the problem. Email is sent from an email client (like MS Outlook, Mac Mail, webmail [if you use a web browser to access your email, that's webmail]), to *your* email server, and then your email server looks for an MX record for the domain that you're sending the message to. If it is not able to find a mail server in an amount of time that it's configured to find one, it will fail with an NDR or Non Delivery Report. Again, this can sometimes be tolerable (aggravating, but tolerable) in a residential environment, but can cause problems in a business or professional environment. If your prospective client is sending out a request for bid via email and you never get yours because your DSL connection was down, you just lost business and your competitor just got a new client.

Ok, so we're all up to speed on some cool new acronyms and we understand what the problem is, so now let's learn how to fix it. As I mentioned before, DNS gives us the ability to setup multiple MX records so that, if one is down, mail will be delivered to an alternate server temporarily. That's where our 1.5 ways to save the mail starts.

Option 1 - Secondary MX only - We setup a primary MX record that points to our actual mail server (often, a Microsoft Small Business Server, Microsoft Exchange Server or Linux / Unix MTA). This will be our 'Primary MX' record, and will have the lowest metric. We then setup a secondary MX record that points to an offsite server. This can be a second office (branch office), your hosting provider (this is a service that Cyber Tech Cafe can provide) or a third party. This will point to a server that's configured to receive your email if your primary MX is down and store it until your primary MX comes back online. The secondary (or tertiary, etc.) will periodically query your primary and will automatically begin to offload the messages [to the primary] when it comes back up. The pros and cons here are :
Pros

• Operates at a domain level so, once it's configured, it doesn't have to be changed when users / mailboxes are added or removed
• Typically very cheap to setup

Cons

• Generally, no access to messages that are 'in queue'

Option 1.5 - Secondary MX with Access to Email - As you may note, the basics here are the same. We setup a primary, secondary (tertiary, etc.) MX record for our domain and configure those backups to store email for us when / if our primary MX goes down. The difference here though is that we have access to the mail while it's on the secondary (or tertiary, etc.) servers. This access can be as simple as a forward to a 'standby' account (e.g., a Gmail account) or even POP3 or IMAP4 access (the latter would get a bit complicated) to the messages while they're on the backup servers. The pros and cons here are:
Pros

• Access to emails on the secondary servers while the primary is unavailable

Cons

• Additional initial configuration
• Would require configuration changes / updates each time a user or mailbox (alias, etc.) is added / removed
• Would require additional cost to accommodate for the POP3 / IMAP4 access

We typically recommend clients who host their own mail server to have at least one level of redundancy for their MX. We provide single tier backup at no cost to our hosting customers (upon request), and can provide up to 3 tier backup for $4.00 per month. If you'd like to hear more or if you'd like to get one or multiple backup MX records setup for your office, let us know.