Anyone who sends out HTML newsletters knows that it is all too easy for a spam filter to determine that your content is spam. If your domain sends too many emails that are considered “spam” you may become blacklisted, and all of your emails, even individual ones may be blocked entirely. The spam filters are getting smarter and smarter as spammers try different techniques; we will go over a few of these techniques and how to avoid them.

Add your physical address

In the United States this is also the law. If you send out any type of mass email you must provide a physical address as well as an unsubscribe method. Having a physical address also makes you seem more creditable.

Link images to your server instead of attaching them

Using Outlook you can easily create an email with graphics; however, those images are being sent as attachments and increase the file size of the email. Just like webpages, you should try to make your emails as small as possible without sacrificing quality. By linking to the images on your server, the only thing being sent to the user is HTML.

The one downside to this is that when the user goes to view the email, they may have to click a link or button to “Download the Images”.

Do not send out emails via BCC’

One of the great things about Blank Carbon Copy, or BCC, is that you can send out an email to multiple people and those people don’t know who else got the message. So instead of the user getting an email like this:

They get something like this:

The problem here is that only one email was sent, it was just distributed to multiple people. The spam filters don’t see the single address, they see multiple addresses and this raises a red flag. One of the things that mass emailing programs do is that they send each person on your list a unique email. So if you have a list of 500 people, the client will send out 500 emails.

More text than images

I receive a lot of bad spam in my inbox that is just an attached image that has text in it. The reason spammers do this is because the spam filters can’t read the word in the image. As a result emails for pharmaceutical companies used to get though. The people who operate the spam software realized this and when an email comes through that is mostly images, or a single image, it has a much higher chance of being marked as spam.

There should be a healthy mix of images and text; HTML emails is not the place for fancy content text; stick with Arial or Times New Roman… preferably Arial since it is easier to read.

No scripts of any kind

Nothing says “hacker” more than trying to send an email out with JavaScript embedded within. A lot of email providers will delete your message right away and not even let it go to the spam folder if you include scripts. Although JavaScript is a nice client side language it is used a lot on the web for Cross Site Scripting attacks.

Flash objects are also prohibited in most email clients. This seems like a logical step in my mind; I get annoyed by flash advertisements on my favorite websites, I would hate it if I got one in an email. Outlook actually blocks flash elements as well as animated GIFs.

Animated GIFs (you know, the images that have movement) are not a spam indicator, however they may annoy your subscribers. Many email clients and provides actually block them, so use them with caution.

Anything else?

As the spammers get smarter so must the spam blockers. Do you have any tips to make sure your emails don’t get put in the spam folder?

Tags: email, HTMLemail, spam