Email Going to Spam Folders

To stay out of the spam folder, you should not look like a spammer. There are three broad criteria that ISP’s use to route your email:

  • Email Content
  • Sender Reputation
  • DNS Records

By reviewing these three areas and using good email practices, you won’t have to read our spam blacklist removal articles.

Email Content

If you are sending an email about Viagra, your email will probably be going to a spam folder. However, you may be surprised to learn that most modern spam filters do not heavily rely on content. Detecting spam related content is challenging. Spammers constantly change word order or images to get around content filtering. So while some level of content filtering is used, your server’s sending reputation and network information are often more important. Unless you are using “stop words” that have a high association with spam, content is typically not the reason you land in the spam folder.

A few ISPs may look at the ratio of links to text in an email. If you send someone a link, be sure to add a description. Phishing attacks often send out links with very little text. So, if you need to send URLs in your emails, be certain there is also text included.

As with URLs, just sending an image in an email with no text is another red flag. If you send pictures, be sure to provide a comment or two.

Sender Reputation

sender reputationAnti-spam filters keep track of the behavior and spam sent by specific IPs and domains. Behavior based filtering is proving to be one of the most effective tools to combat spam. This method also leverages the input of end-users. For example, if an email recipient flags a message as spam, then that puts a negative mark on your server’s reputation. Too many complaints and your server will be seen as a bad sender.

In addition to filtering based on end-user input, behavior based systems can flag sudden spikes in email traffic. If your server typically sends a 100 emails a day to the ISP and suddenly it is sending 1000’s, there is a good chance that the system has been exploited and/or someone is now spamming from that domain. By looking for differences in behavior, anti-spam tools can clamp down on sudden attacks from otherwise reputable senders.

To check out your sending reputation, you can have a look at Sender Base or Return-Paths’s Sender Score. If your server has a low reputation, delivering email will be difficult and most of it will go to the spam folder. Aside from reputation, some filters may block on behavior. If your server typically sends only a few emails a day to that ISP and then starts sending 100’s, they may temporarily block your email or route it to the spam folder until your sender reputation and behavior adjusts.

A major issue with reputation based sending is when you acquire new servers. IPs are re-used. So while your practices may be good if you inherit a system with a bad IP address, it make take a few days or weeks for an ISP to recognize that the email is no longer junk.

DNS

DNSDNS glues the internet together. To combat spam and phishing attempts, there are a number of DNS records that are good to have in addition to your basic A record for your domain. To help with DNS issues, there are many easy-to-use online, network diagnostics tools you can use.

For email delivery, you will want to be sure that the domain you are sending from has an A record. Often the server you are sending from may not have the same fully qualified domain as your email domain. For example, if you use plesk.domain.com for your Plesk server’s hostname, you will need an A record for plesk.domain.com. Receiving email systems will check for A records for both your domain and the hostname of the sending server.

Some ISPs will require that you have reverse DNS (PTR record) configured for the email server’s IP address. Reverse DNS is typically handled by your server provider and not set on your control panel. If unsure about your reverse DNS settings, ask your hosting provider. At rackAID, we automatically setup reverse DNS for any of our managed hosting clients.

SPF, Domain Keys, and DKIM may also keep your emails out of the junk folders. Sender Policy Framework was created to reduce phishing. The full scope of setting up SPF is beyond this post but you may need to have SPF or Sender-ID records to improve email delivery. Domain Keys and DKIM is a way to assure that email integrity. While you need more than just DNS to implement DKIM, DNS records are required. If you use SPF and DKIM, test it. Having these records mis-configured can actually do more harm than good.

Your Tips

Have you found ways to stay out of the spam folder? We would love to hear how you keep email going to spam folders.

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