This blog post mainly delves on how spam filters treat your emails.
For marketing and sales people email spam is a big impediment in them reaching out to newer customers and are often clueless as to why their emails are going to spam.
Even for perfectly crafted emails that one sends, chances are high that the email doesn’t reach prospects inbox.
It often gets frustrating, because there is no feedback mechanism to understand why an email that you have sent has reached inbox or spam.
Every email that is received by the email client (gmail, outlook etc) is passed through series of filters called spam filters and it is these filters that decide whether an email should be sent to inbox or spam based on some checks.
Spam filters basically grade your email based on content, links (checks for any phishing activity), authentication and reputation.
For a new email id, the reputation score is neutral and it gets changed over time depending on your sending activity. As you start sending emails: reputation of your sending IP & domain, list accuracy, spam complaint rates and email volume all influence your overall reputation score.
Of these, one of the principal factors in driving down sender’s reputation and deliverability is their Spam email complaint rate.
Let’s look at how Outlook email client treats your emails:
Microsoft sends every incoming message through their spam filters and sends the findings of spam filters along with the incoming message to the recipient’s email account. When you look at message details of an email received in recipient’s email account, you can find this :
You can see that it contains information about Authentication results like SPF, DKIM and Dmarc. SPF, DKIM and Dmarc are used to accertain if the sender is indeed allowed to send emails from that IP/Domain.
Microsoft also adds certain other headers to its message. These are:
- X-ForeFront Anti-Spam Report
- X-Microsoft Anti-Spam.
These headers give additional information for the recipient’s email administrators as to how their email has been processed.
Read on to know more technical details about these headers or skip these details and go directly to the end for our conclusion.
X-ForeFront Anti Spam Report :
CIP [IP Address]
IPV — CAL ( Message is allowed through Spam Filters because IP is listed in the allow list) ; NLI ( Message is allowed through Spam Filters because Ip is not listed on IP reputation list)
SFV — SFE ( Filtering is skipped and the message is sent to the inbox as the sender is on the individuals safe sender list ); SPM ( Message is marked as spam by the content filter); NSPM ( Message is marked as Non-Spam and is sent )
SCL : Spam Confidence Level of the message — When an email message is sent through spam filters, it will be assigned a spam score. That score is mapped to a Spam Confidence Level and is sent further to the service. Based on the SCL value the service will decide in which folder should it place the email.
An SCL of -1,0,1 indicates that your email is not spam and should be in inbox.
An SCL of 5,6 indicates that your email is suspected to be spam.
An SCL of 7,8,9 indicates that your email is definitely spam. (2,3,4 are not used)
X-Microsoft Anti-Spam Header:
BCL : The Bulk Complaint Level (BCL) of the message.
PCL : The Phishing Confidence Level (PCL) value of the message.
BCL ( Bulk Complaint Rate) — Bulk mailers usually vary in the sending patterns, content creation and list acquisition practices. Certain bulk senders send unsolicited irrelevant emails to people which resembles spam and generate many complaints from recipients. Messages from the bulk mailers are assigned a bulk complaint level rating.
(It basically means that a number of your prospects have marked your emails as spam)
BCL are usually assigned values between 0–9 and where 0 indicates that the sender isn’t a bulk sender and 9 indicates that it is likely to generate many complaints from recipients
Phishing Confidence Level (PCL) — Phishing Confidence Level indicates whether a message is a phishing message or not. Its status can be any of the following numbers
In the above images you can see that SCL is -1, BCL is 0 and PCL is 0. indicating that the email is received is not spam and is from a known sender.
So as to analyse what constitutes SPAM we have noted SCL,BCL,PCL values from different emails from various outlook inboxes.
TL;DR — For your emails to reach inbox rather than spam folder,
- checks for SPF, DKIM, Dmarc should ‘pass’;
- SCL value should be 1,0,-1;
- BCL value should be less than 3,
- PCL value should be less than 3
In this case, the sender’s IP address is not listed in any IP blacklists and the email is marked as non-spam by the content-filters(SFV : NSPM) and has a spam confidence level of 1(SCL : 1) indicating a good spam score. However this email generates too many complaints from recipients(BCL : 6).
Outlook Spam filter has not marked this email as spam despite a high spam complaint rate. Whereas Gmail’s spam filter has classified it as spam.
This is an email sent by a bulk sender indicated by SFV: BLK in X-ForeFront Anti-spam Report and has a high Spam Confidence Level of 6 which means that the email has been sent to spam.
Again this is an email which is a Bulk mail indicated by the SFV: BLK and has high Spam Confidence Level of 6 and has a moderate bulk complaints.
This email has landed in the spam folder.
If you just want a quick solution to understand problems with your email. SmartReach.io provides free spam test along with email automation campaigns. They help you fix problems with your email authentication, content and help you identify which email blacklists your IP is in