The first two blogs of Deliverability series were specifically focusing the dynamics of building and maintaining a hygienic list, the third blog is more towards the role of spam filters in deliverability. Spam filters proactively monitor the incoming emails to detect the unsolicited emails and to route it towards the spam/junk folder. Like other automated programs, it works a certain way to identify the possibilities of incoming email as spam. Before we delve into the discussion of how spam filters work and how to avoid them getting triggered, let’s first analyze what spam is?

Spam Filters

Large percentage of email messages sent globally is categorized as spam. In some of the countries, commercial email industry is governed by legislation and regulation. Some of these countries are USA (CAN SPAM ACT), Canada (CASL), Australia (Spam Act 2003), United Kingdom (EC Directive 2003) and Germany (Federal Data Protection Act). All the laws and regulations may have their own peculiarities, but collectively all of the anti-spam laws emphasize on the use of opt-in forms to collect contact’s information, send permission based emails only, and provide an easy way to opt-out as well.

So more precisely, spam is an unsolicited and irrelevant electronic message sent in bulk to large number of contacts, and without their prior permission. So the crux of spam filters is that they are striving to limit the possibilities of such unsolicited and irrelevant emails to enter recipient’s inbox. Spam filters are getting more efficient by the time and utilizing variety of ways to identify and categorize the email spam accurately, but they aren’t perfect and it is often observed that even some of the major ISPs route a completely legitimate message to spam/junk folder. Therefore, knowing about spam filters is important for achieving target of high inboxing. Spam filters don’t offer the details of practices to follow and things to avoid; but still it is obvious that they are programmed to implement the anti-spam laws in an effective way. Here are few of the factors spam filters would take into account to determine if the incoming message is spam.

Message Header/ Originating Source

Spammers mostly conceal the message originating information to avoid getting traced. Therefore spam filters put effective tools to scrutinize the email header and the relay information left by the sending server. It takes several useful factors into consideration to look into from and reply to (return-path) information, subject line and unsubscribe header. It looks for the validity of DKIM signature and also if the originating server is allowed to send on behalf of the sender (SPF). Spam filter triggers if it finds that the email header is forged and the incoming email is potentially a spam. So always avoid using deceptive information in your header.

IP Address

Moreover, if you are using an IP address that has already been identified for relaying spam, trapped and listed publically by one or more recognized blacklist(s), your email is more likely to be ended up being filtered as spam. Always rely on the IPs having clean sending reputation and history.

Content Filters

Content filters are working from the very beginning to distinguish legit emails from the email with spammy stuff. Sender behavior have educated the spam filters to detect the typical kind of email content used to steal recipient’s identity or important information by making him to click on a fraudulent link. Or the type of words/ phrases used in the large scale advertisement campaigns about easy money making, earing, trading and more.

More clued-up spam filters vigilantly detect words and phrases used by the spammers, and place the email with such words/phrases in spam/junk folder. Unluckily, we don’t have a complete list of words/phrases filters consider as spam, but still large number of such words/terms are available on the internet to avoid them getting used in the email content.

The content filters can be discussed for the extra ability to be triggered for certain type of images and messy codes. Therefore, do properly format the email content; avoid using forms, all letters in caps, fonts of too large sizes and doing such other strange things with the email content like bilking words/texts. Make use of a subject line that clearly denotes to the content of your email campaign. Avoid all kind of tricky and deceptive practices.

There are certain other clues that the sender would give to the spam filter to identify the email as spam. But since, working of every spam filter is different from the other and spam filters don’t publish any such detailed criteria to meet for avoiding getting spammed. We can only follow the largely accepted industry standards, spam laws and best practices. From getting this blog lengthier, let’s discuss general suggestions and Mumara’s features to get the email past the spam filter.

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