Knowledge is Power Part II - Hotmail Spam Filters

Hello again. In my last article, I discussed the mechanism of how AOL Spam Filters operate. Continuing on the subject on Spam Filters, in this issue I will focus on Microsoft’s Hotmail Filter and delve into the basic Anti-Spam architecture and how it affects your email campaigns.

Microsoft uses multi-level spam filters for all inbound emails. The first level is the blacklist and volume filter check -- where your IP and sender domain are checked against Microsoft’s internal and 3rd party blacklists. Both throttling and blocking of connecting Mail Transfer Agent (MTAs) also happens at this level.

The email then passes through Brightmail’s spam filter and Smart Screen (Microsoft’s proprietary content Spam filter) and then is checked for whitelisting of the IP and sender domain against safe-lists and Sender Score. After passing this phase, it is verified for authentication i.e. SenderID -- which confirms sender domain is approved to be sent via the sending IP address. The recipient filter then checks if the from-address has been setup in the Recipient’s address book. A score is produced which determines the placement of your mail (Inbox, Junk or Trash).

Hotmail uses mailing history as one of the main determinant for placement of mails into the inbox. New IPs with no mailing history has a harder time for inbox placement compared to an old IP with reputation. Mailers can achieve and build this reputation by sending smaller volume regularly (5-10K per day) rather than large volumes infrequently. The consistency in the mailing has proved to have better performance on campaigns due to higher deliverability. Also keep in mind that, Hotmail does not use user’s address book as the determinant factor for mail placement unlike AOL -- as the address book is referenced late in the filtering hierarchy.

Over 30% of spam today is image spam, messages containing solely of one or multiple images, and Hotmail flags 90% of emails a day as spam. SPF, SenderID, and DomainKeys/DKIM records are very important to get your emails delivered along with Sender Score, Bonded Sender programs and Reputation of the sender.

Finally, the key to the inbox of Hotmail is heavily dependent on the reputation. The reputation metrics consists for three things:

-- Spam Complaints: Number of users reporting your campaign as spam
-- Unknown User Bournce Rates: Bad/Inactive email addresses
-- Spam Traps: Emails addresses acquired by harvesting or that was purchased

This is where emphasis on managing feedback loops, bounce management, and carefully selecting your data providers becomes critical and essential to building your reputation.

Stay off the Dreaded Blacklist

Most email marketers know about the Can-Spam Act. If you want to stay off the dreaded Blacklist you should follow these simple protocols. When it comes to being in compliance with the Can-Spam act it is simple. You don’t want to run the risk of receiving a penalty that can cost your company time and expense .You want to make sure that you are on the whitelist or that the customer has your domain saved in the address book.

Simple steps you can follow:

• Keep an eye on your reputation- Make sure you stay up on the law of the Can-Spam act.


• Allow users to add their email to your list via your web site.


• Collect email addresses when in contact with customers to build your list of wanted users.


• Do not use misleading subject lines or headers


- The subject line should accurately state what content the email contains. Use Call to action to increase Opens.

- The “From” , “To” and “Reply-to” email address and domain should state the company the email is coming from


• There should always be a valid physical address on each email sent out.


• Allow your users to opt out on receiving emails. This can lessen the chance of more users placing your email in spam to get rid of receiving emails from your company.


• If a user chooses to unsubscribe or opt out on receiving emails from your company you should honor the request within 10 days the latest.


• Manage and know what other companies you have hired to do any email advertising for your company.

- You want to make sure that they are in compliance as well

It is best practice to stay off spam lists. You want your message to be heard. Being in compliance with the Can-Spam Act will help you stay off the dreaded Blacklist. For more information search Can-Spam Act.

Author: Amarilys Rivera
Editor: Roopal Rawani

Knowledge is Power Part I - AOL Spam Filters

Let me try and shed some light on AOL’s basic anti-spam architecture as a process flow and how it affects inbound email. There are three main types of spam filters that AOL uses i.e. blacklist filter, reputation filter, and a whitelist filter.

A blacklist filter is when an email is checked against AOL’s internal blacklist. If the sender domain is blacklisted, the mail will be blocked. The reputation filter then reviews the reputation metrics in the form of “abuse data” (spam complaints and spam traps). Once it passes the two filters, the domain is checked by a whitelist filter where it runs a check if the from-address (consisting of the domain) is in the recipient’s address book or if the IP and Domain are on any of their whitelists. Being on AOL’s whitelist allows emails to go through and be place directly into the inboxes with images displayed.

There are more filters used by AOL. However, if enhanced whitelisting status has been achieved with AOL then some or all of these following filters are bypassed. These filters include volume filters, content filters and recipient filters. If the sender domain or IP is not on AOL’s whitelist, the email is then routed through AOL's volume filters. The content filters then applies its proprietary content filtering and Bayesian filtering rules. Recipient Filters are when an email may pass a domain block, recipients personal Bayesian (defined by previous actions) rules or recipient’s personal filters. If an email does not pass these filters the email will be delivered, but then placed in the spam folder or completely blocked.

The best way to improve deliverability with AOL is to setup a Feedback Loop with them to reduce the number of complaints they receive from their end users. AOL has also planned to introduce SPF & DKIM into the reputation model soon. This means they will be using it as a means of authentication and reputation checking for connecting IPs as an added data point to help them determine the final status of email. Keeping content relevant and fresh along with emailing to active users also helps in increasing deliverability.

Common Deliverability Issues Revealed

Wonder what causes delivery issues? Here are just a few reasons as to why your message may not be delivered properly or in a timely manner to the inbox:

Sender Reputation - This element consists of list hygiene, message quality, subscriber engagement and complaint rates. Keeping a good standing with ISPs is important in determining whether your message gets to the Inbox, goes sent to spam, or gets blocked all together.

Spam Trap – ISPs frequently use deactivated email address accounts with the intention of trapping illegitimate senders.  Using purchased lists, whose integrity are in question, is not advised. It’s better to have a healthy list than a long list.

Volume – Spammers tend to send in large bulk trying to hit as many people as they can with the same sort of offers. You might have a large list but if you cleanse on a regular basis and keep a good reputation with the ISPs it will help avoid being blocked.

Authentication – Allows the ISP to know that you, the sender, are in fact the actual sender. Make sure you receive the proper authentication before sending in bulk.

Hardbounce rate – Removing unknown email addresses can help avoid getting trapped in a spam filters. Cleansing your list is important to avoid delivery issues.

Complaint Rate – Having users unsubscribe should not be seen as a bad thing. If users unsubscribed from receiving your emails this is the best and friendliest way. Allowing the users to unsubscribe easily may help with lowering the chances of them complaining as spam.

Consider these reasons regarding why your message may be seeing delivery issues and work toward establishing a better reputation with the ISPs. Here at KobeMail we understand these causes and work closely with our clients on eliminating the above causes.

Outlook 2003 says Junk It!

Testing.........
Gmail …: Inbox
Yahoo …: Inbox
Hotmail …: Inbox
AOL ...: Inbox
Outlook 2003 …: JUNK!

Time and time again we face the same problem of creatives being classified as Junk mail on desktop applications -- when they are reaching the Inbox of major ISPs. While whitelisting and authentication entries can take you to inboxes on large ISPs, it does not help much on desktop applications.

Outlook 2003 is one of the more used email desktop applications. The first thing we have to understand about desktop applications is that:

:: The filtering aspects are different
:: The filters are user defined

…and outlook 2003 is no different. Over a 100 million people use Outlook as their email application which means it is likely that your users may be among them. Getting your email communication out to them is of utmost importance, as one user not receiving the communication is one lost source of revenue – if you are a business.

We have to better understand how we can reach these users; we have to understand the tools they use to read your communication. Here is some insight of how an outlook filter works, and why your creatives maybe rotting in a Junk folder waiting to be deleted.

Message Sending Time Check – Weekends are a bad time to send a campaign to your users who use Outlook. The filters give it a higher score and are more likely to end up in the Junk folder than if the mailing was sent on a weekday.

Upper Case in Messages - If the message contains around 25% or more uppercase words, it classifies the message as SPAM. Avoid Uppercases both in subject lines and body of the messages as a rule of thumb for all your communication.

Numbers and Symbols - If the content has close to 8% or more numbers and symbols, the message is classified as SPAM. As an example for $100, avoid using “$” signs or “100” values – instead use “One hundred dollars”.

Duplicate Check – Outlook filters checks for duplicates. The more the repetition of the same word, the higher the weighted SPAM score and more likely the message will end up in Junk.

User Settings - User settings most often send the emails to Junk. Ask your users to whitelist your IP or domain.

The above are some of the pointers for better deliverability to the inbox in Outlook. Look to next week when I delve into the filter aspects of Hotmail Live, Yahoo, Comcast and AOL --- and not in that specific order.

Happy Mailing!

Email Campaign Creative - 101 - Part Deux

As promised here is the continuation from my last post on creating effective creatives optimized for deliverability. These are some of the things I continually advise my production team and clients to focus on. Although following some of these may cause the creatives to loose some luster, at the end of the day deliverability is all that matters, and getting through to your consumers. So here are some more tid bits for your creatives --

Height and Length of Logo / Banner: The length of the logo/banner should be equal or less than 600 pixels. The width should be proportionate and ideally under 100 pixel range. Anything over will be one blocked image in the preview pane until the user allows images to be downloaded

Font Size: Medium font size is recommended for all creative, as large fonts within the creative affect the SPAM score and increase based on repetitive usage.

Tables: Avoid using excessive tables and/or nested tables within the creative. When images are blocked, this can cause the creatives to look broken and the text out of place.

Image Dimensions: The height and width should be defined for all images in the creative within the image source tag. This will make the creative text readable even if the images are blocked.

RTF Images: RTF images are not recommended as it's become a spamming mechanism -- so while it can get images opened, you risk getting put on a SPAM list by a user who has created a filter for this.

Email Campaign Creative - 101 - Part 1

Create campaigns that are great looking with a focus on deliverability and maintaining creative conformity when received by the ISPs. Here are some of my suggestions:

CSS Styles: Yes they look GREAT when used on a website but for email creatives its a big AVOID. Creatives that are heavy on the CSS styles have a low text to html ratio low. CSS should be avoided in emails as they will be ignored by most web clients. Style sheets (inline or external) will be ignored by Yahoo/Gmail. Instead it is advised to use inline table styles for all your styling requirements within a creative.

Clean and Smooth Transition: Creatives should be clean and must have smooth transition between image and text from top to bottom ---limiting to a maximum of one column where text is displayed. Adding multiple columns of text and images causes the creative to break when the images are not displayed -- currently a standard practice by most web based and pc based email clients. To attain a cleaner and more presentable look, we recommend that you do not exceed more than one column for your email creatives where text is displayed. This will not only make your creatives look more professional, but also when images are disabled it will make the email acceptable as well as readable. It also makes it easier to convince the ISPs that the Newsletter is legitimate--because of the look of the creative--and not intended as SPAM, when someone reports the email.

Backgrounds and Alignment: Colorful backgrounds again raise the SPAM scores precipitously. A white background is the lowest scoring color within a creative. Also, most SPAM creatives are centered. We advise that you left align your creatives to make it look more legitimate form of communication. Developing creatives with a white background and aligning the contents to the left, makes your email campaign look less like a SPAM mailing. The combination of these changes i.e. of background and alignment will have a positive effect on your deliverability by decreasing your SPAM score

Text to HTML Ratio: Creatives must have images and text in a creative. A 60-40 rule should always be followed while creating html based creatives. Most SPAM messages are center aligned image only, and hence is a SPAM indicator for various filters.

The second part will continue on this post.

Happy Mailing!