DNS stands for Domain Name System, which is basically the protocol computers use to connect to each other across the web. If you sent an email to "JaneDoe@AnySite.com" your mail server would do a DNS lookup on "AnySite.com" so it would know to actually send your message to the mail server at "123.45.67.890". That mail server would then route your message to its user named "JaneDoe". DNS works both ways - the receiving email server has an IP number and the sending email server has an IP number. Until a few years ago, the IP address of the sending email server wasn't all that important. But, with the onslaught of spam, all that has changed.
Today, most mail servers will check the IP address of the sending server before accepting the message, to see if the mail is coming from a static or dynamic IP address. The receiving mail server performs a reverse DNS lookup - it checks the IP address that the email is coming from to make sure that address belongs to the sending mail server.
If an email message is claiming to be from "YourCompany.com" the receiving mail server will make sure the IP address does indeed belong to YourCompany.com. It's easy to check this when the sending IP address is a static one. A static IP address belongs to one particular computer and the address always stays the same.
However, a dynamic IP address changes every time the computer connects to a network or the web. It's not possible to perform a reverse DNS lookup on a dynamic IP address. Dynamic IP addresses are used by individuals with dial-up or DSL accounts on personal computers. Unfortunately, they are also used by spammers. So if a bulk of mail is coming from a dynamic IP address, there's a good chance the mail will be sent immediately to the spam folder.
If you're sending your marketing messages directly from your own computer using the email configuration provided by your internet service provider, you're probably using a dynamic IP address with no reverse DNS lookup. Now, this isn't a problem if you're sending one-off messages to Aunt Betty, but it does become a problem if you're sending a bulk email to your entire client database. If you're using a from address like "JoeSmith@YourCompany.com", since the dynamic IP address assigned by your ISP does not belong to "YourCompany.com", there's a good chance your message will be rejected.
You might think you can resolve this issue simply by using "JoeSmith@YourISP.com" as your from address; unfortunately, this doesn't always work either. In an effort to protect their users from unwanted spam, ISPs treat bulk email differently than they do individual messages. And, since the sending IP address is still a dynamic one, there's a good chance your message will still end up in the spam folder.
The best thing to do is to ensure that your website's DNS entry is complete and is capable of a reverse lookup. Then use your webhost's email server to send all your marketing messages. Check with your web hosting company's technical department to verify that your website and its corresponding email server are both using static IP addresses with complete DNS entries. And while you're at it, ask them to set up an SPF record for your domain.
Using complete DNS entries will not guarantee that your email is delivered 100% of the time, since there are still many more issues that affect deliverability. But it's one step toward reducing the likelihood that your email will be mistaken as spam.
Time to implement: this shouldn't require more than a fast phone to your webhost's technical department. If you've been your ISP's mail configuration, your webhost can walk you through the correct steps for setting up your email client to use your host email server
